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John A. WIDTSOE
Dry Farming
Dry Farming
Born 1674; died 1741. His methods of
soil tillage lie at the foundation of the modern system of
dry-farming.
NEW YORK
THE MACMILLAN COMPANY
1920
All rights reserved
T0
LEAH
THIS BOOK IS INSCRIBED
JUNE 1, 1910
Nearly six tenths of the earth's land surface receive an annual
rainfall of less than twenty inches, and can be reclaimed for
agricultural purposes only by irrigation and dry-farming. A
perfected world-system of irrigation will convert about one tenth
of this vast area into an incomparably fruitful garden, leaving
about one half of the earth's land surface to be reclaimed, if at
all, by the methods of dry-farming. The noble system of modern
agriculture has been constructed almost wholly in countries of
abundant rainfall, and its applications are those demanded for the
agricultural development of humid regions. Until recently
irrigation was given scant attention, and dry-farming, with its
world problem of conquering one half of the earth, was not
considered. These facts furnish the apology for the writing of
this book.
One volume, only, in this world of many books, and that less than
a year old, is devoted to the exposition of the accepted dry-farm
practices of to-day.
The book now offered is the first attempt to assemble and organize
the known facts of science in their relation to the production of
plants, without irrigation, in regions of limited rainfall. The
needs of the actual farmer, who must understand the principles
before his practices can be wholly satisfactory, have been kept in
view primarily; but it is hoped that the enlarging group of
dry-farm investigators will also be helped by this presentation of
the principles of dry-farming. The subject is now growing so
rapidly that there will soon be room for two classes of treatment:
one for the farmer, and one for the technical student.
This book has been written far from large libraries, and the
material has been drawn from the available sources. Specific
references are not given in the text, but the names of
investigators or institutions are found with nearly all statements
of fact. The files of the Experiment Station Record and Der
Jahresbericht der Agrikultur Chemie have taken the place of the
more desirable original publications. Free use has been made of
the publications of the experiment stations and the United States
Department of Agriculture. Inspiration and suggestions have been
sought and found constantly in the works of the princes of
American soil investigation, Hilgard of California and King of
Wisconsin. I am under deep obligation, for assistance rendered, to
numerous friends in all parts of the country, especially to
Professor L. A. Merrill, with whom I have collaborated for many
years in the study of the possibilities of dry-farming in Western
America.
The possibilities of dry-farming are stupendous. In the strength
of youth we may have felt envious of the great ones of old; of
Columbus looking upon the shadow of the greatest continent; of
Balboa shouting greetings to the resting Pacific; of Father
Escalante, pondering upon the mystery of the world, alone, near
the shores of America's Dead Sea. We need harbor no such envyings,
for in the conquest of the nonirrigated and nonirrigable desert
are offered as fine opportunities as the world has known to the
makers and shakers of empires. We stand before an undiscovered
land; through the restless, ascending currents of heated desert
air the vision comes and goes. With striving eyes the desert is
seen covered with blossoming fields, with churches and homes and
schools, and, in the distance, with the vision is heard the
laughter of happy children.
The desert will be conquered.
JOHN A. WIDTSOE.
June 1, 1910.
1. Dry Farming
Defined
2. Theoretical Basis
of Dry-Farming
3. Dry-farm
Areas--Rainfall
4. Dry-farm
Areas--General Climatic Features
5. Dry-farm Soils
6. Root-systems of
Plants
7. Storing Water in
the Soil
8. Regulating the
Evaporation
9. Regulating the
Transpiration
10. Plowing and Fallowing
11. Sowing and Harvesting
12. Crops for Dry-farming
13. The Composition of
Dry-farm Crops
14. Maintaining the
Soil-fertility
15. Implements for
Dry-farming
16. Irrigation and
Dry-farming
17. The History of
Dry-farming
18. The Present Status of
Dry Farming
19. The Year of Drouth
20. Dry-farming in a
Nutshell
DRY-FARMING, as at present understood, is the profitable
production of useful crops, without irrigation, on lands that
receive annually a rainfall of 20 inches or less. In districts of
torrential rains, high winds, unfavorable distribution of the
rainfall, or other water-dissipating factors, the term
"dry-farming" is also properly applied to farming without
irrigation under an annual precipitation of 25 or even 30 inches.
There is no sharp demarcation between dry- and humid-farming.
When the annual precipitation is under 20 inches, the methods of
dry-farming are usually indispensable. When it is over 30 inches,
the methods of humid-farming are employed; in places where the
annual precipitation is between 20 and 30 inches, the methods to
be used depend chiefly on local conditions affecting the
conservation of soil moisture. Dry-farming, however, always
implies farming under a comparatively small annual rainfall.
The term "dry-farming" is, of course, a misnomer. In reality it is
farming under drier conditions than those prevailing in the
countries in which scientific agriculture originated. Many
suggestions for a better name have been made. "Scientific
agriculture" has-been proposed, but all agriculture should be
scientific, and agriculture without irrigation in an arid country
has no right to lay sole claim to so general a title. "Dry-land
agriculture," which has also been suggested, is no improvement
over "dry-farming," as it is longer and also carries with it the
idea of dryness. Instead of the name "dry-farming" it would,
perhaps, be better to use the names, "arid-farming."
"semiarid-farming," "humid-farming," and "irrigation-farming,"
according to the climatic conditions prevailing in various parts
of the world. However, at the present time the name "dry-farming"
is in such general use that it would seem unwise to suggest any
change. It should be used with the distinct understanding that as
far as the word "dry" is concerned it is a misnomer. When the two
words are hyphenated, however, a compound technical
term--"dry-farming"--is secured which has a meaning of its own,
such as we have just defined it to be; and "dry-farming,"
therefore, becomes an addition to the lexicon.
Dry- versus humid-farming
Dry-farming, as a distinct branch of agriculture, has for its
purpose the reclamation, for the use of man, of the vast
unirrigable "desert" or "semi-desert" areas of the world, which
until recently were considered hopelessly barren. The great
underlying principles of agriculture are the same the world over,
yet the emphasis to be placed on the different agricultural
theories and practices must be shifted in accordance with regional
conditions. The agricultural problem of first importance in humid
regions is the maintenance of soil fertility; and since modern
agriculture was developed almost wholly under humid conditions,
the system of scientific agriculture has for its central idea the
maintenance of soil fertility. In arid regions, on the other hand,
the conservation of the natural water precipitation for crop
production is the important problem; and a new system of
agriculture must therefore be constructed, on the basis of the old
principles, but with the conservation of the natural precipitation
as the central idea. The system of dry-farming must marshal and
organize all the established facts of science for the better
utilization, in plant growth, of a limited rainfall. The excellent
teachings of humid agriculture respecting the maintenance of soil
fertility will be of high value in the development of dry-farming,
and the firm establishment of right methods of conserving and
using the natural precipitation will undoubtedly have a beneficial
effect upon the practice of humid agriculture.
The problems of dry-farming
The dry-farmer, at the outset, should know with comparative
accuracy the annual rainfall over the area that he intends to
cultivate. He must also have a good acquaintance with the nature
of the soil, not only as regards its plant-food content, but as to
its power to receive and retain the water from rain and snow. In
fact, a knowledge of the soil is indispensable in successful
dry-farming. Only by such knowledge of the rainfall and the soil
is he able to adapt the principles outlined in this volume to his
special needs.
Since, under dry-farm conditions, water is the limiting factor of
production, the primary problem of dry-farming is the most
effective storage in the soil of the natural precipitation. Only
the water, safely stored in the soil within reach of the roots,
can be used in crop production. Of nearly equal importance is the
problem of keeping the water in the soil until it is needed by
plants. During the growing season, water may be lost from the soil
by downward drainage or by evaporation from the surface. It
becomes necessary, therefore, to determine under what conditions
the natural precipitation stored in the soil moves downward and by
what means surface evaporation may be prevented or regulated. The
soil-water, of real use to plants, is that taken up by the roots
and finally evaporated from the leaves. A large part of the water
stored in the soil is thus used. The methods whereby this direct
draft of plants on the soil-moisture may be regulated are,
naturally, of the utmost importance to the dry-farmer, and they
constitute another vital problem of the science of dry-farming.
The relation of crops to the prevailing conditions of arid lands
offers another group of important dry-farm problems. Some plants
use much less water than others. Some attain maturity quickly, and
in that way become desirable for dry-farming. Still other crops,
grown under humid conditions, may easily be adapted to dry-farming
conditions, if the correct methods are employed, and in a few
seasons may be made valuable dry-farm crops. The individual
characteristics of each crop should be known as they relate
themselves to a low rainfall and arid soils.
After a crop has been chosen, skill and knowledge are needed in
the proper seeding, tillage, and harvesting of the crop. Failures
frequently result from the want of adapting the crop treatment to
arid conditions.
After the crop has been gathered and stored, its proper use is
another problem for the dry-farmer. The composition of dry-farm
crops is different from that of crops grown with an abundance of
water. Usually, dry-farm crops are much more nutritious and
therefore should command a higher price in the markets, or should
be fed to stock in corresponding proportions and combinations.
The fundamental problems of dry-farming are, then, the storage in
the soil of a small annual rainfall; the retention in the soil of
the moisture until it is needed by plants; the prevention of the
direct evaporation of soil-moisture during; the growing season;
the regulation of the amount of water drawn from the soil by
plants; the choice of crops suitable for growth under arid
conditions; the application of suitable crop treatments, and the
disposal of dry-farm products, based upon the superior composition
of plants grown with small amounts of water. Around these
fundamental problems cluster a host of minor, though also
important, problems. When the methods of dry-farming are
understood and practiced, the practice is always successful; but
it requires more intelligence, more implicit obedience to nature's
laws, and greater vigilance, than farming in countries of abundant
rainfall.
The chapters that follow will deal almost wholly with the problems
above outlined as they present themselves in the construction of a
rational system of farming without irrigation in countries of
limited rainfall.
THE confidence with which scientific investigators, familiar with
the arid regions, have attacked the problems of dry-farming rests
largely on the known relationship of the water requirements of
plants to the natural precipitation of rain and snow. It is a most
elementary fact of plant physiology that no plant can live and
grow unless it has at its disposal a sufficient amount of water.
The water used by plants is almost entirely taken from the soil by
the minute root-hairs radiating from the roots. The water thus
taken into the plants is passed upward through the stem to the
leaves, where it is finally evaporated. There is, therefore, a
more or less constant stream of water passing through the plant
from the roots to the leaves.
By various methods it is possible to measure the water thus taken
from the soil. While this process of taking water from the soil is
going on within the plant, a certain amount of soil-moisture is
also lost by direct evaporation from the soil surface. In dry-farm
sections, soil-moisture is lost only by these two methods; for
wherever the rainfall is sufficient to cause drainage from deep
soils, humid conditions prevail.
Water for one pound dry matter
Many experiments have been conducted to determine the amount of
water used in the production of one pound of dry plant substance.
Generally, the method of the experiments has been to grow plants
in large pots containing weighed quantities of soil. As needed,
weighed amounts of water were added to the pots. To determine the
loss of water, the pots were weighed at regular intervals of three
days to one week. At harvest time, the weight of dry matter was
carefully determined for each pot. Since the water lost by the
pots was also known, the pounds of water used for the production
of every pound of dry matter were readily calculated.
The first reliable experiments of the kind were undertaken under
humid conditions in Germany and other European countries. From the
mass of results, some have been selected and presented in the
following table. The work was done by the famous German
investigators, Wollny, Hellriegel, and Sorauer, in the early
eighties of the last century. In every case, the numbers in the
table represent the number of pounds of water used for the
production of one pound of ripened dry substance:
| Wollny | Hellreigel | Sorauer | |
| Wheat | 338 | 459 | |
| Oats | 665 | 376 | 569 |
| Barley | 310 | 431 | |
| Rye | 774 | 353 | 236 |
| Corn | 233 | ||
| Buckwheat | 646 | 363 | |
| Peas | 416 | 273 | |
| Horsebeans | 282 | ||
| Red clover | 310 | ||
| Sunflowers | 490 | ||
| Millet | 447 |
Oats 385 Barley 464 Corn 271 Peas 477 Clover 576 Potatoes 385
The figures in the above table,
averaging about 446 pounds, indicate that very nearly the same
quantity of water is required for the production of crops in
Wisconsin as in Germany. The Wisconsin results tend to be somewhat
higher than those obtained in Europe, but the difference is small.
It is a settled principle of science, as will be more fully
discussed later, that the amount of water evaporated from the soil
and transpired by plant leaves increases materially with an
increase in the average temperature during the growing season, and
is much higher under a clear sky and in districts where the
atmosphere is dry. Wherever dry-farming is likely to be practiced,
a moderately high temperature, a cloudless sky, and a dry
atmosphere are the prevailing conditions. It appeared probable
therefore, that in arid countries the amount of water required for
the production of one pound of dry matter would be higher than in
the humid regions of Germany and Wisconsin. To secure information
on this subject, Widtsoe and Merrill undertook, in 1900, a series
of experiments in Utah, which were conducted upon the plan of the
earlier experimenters. An average statement of the results of six
years' experimentation is given in the subjoined table, showing
the number of pounds of water required for one pound of dry matter
on fertile soils:--
Wheat 1048 Corn 589 Peas 1118 Sugar Beets 630
These Utah findings support strongly the doctrine that the amount of water required for the production of each pound of dry matter is very much larger under arid conditions, as in Utah, than under humid conditions, as in Germany or Wisconsin. It must be observed, however, that in all of these experiments the plants were supplied with water in a somewhat wasteful manner; that is, they were given an abundance of water, and used the largest quantity possible under the prevailing conditions. No attempt of any kind was made to economize water. The results, therefore, represent maximum results and can be safely used as such. Moreover, the methods of dry-farming, involving the storage of water in deep soils and systematic cultivation, were not employed. The experiments, both in Europe and America, rather represent irrigated conditions. There are good reasons for believing that in Germany, Wisconsin, and Utah the amounts above given can be materially reduced by the employment of proper cultural methods.
[ Photo -- The water in the large bottle would be
required to produce the grain in the small bottle. ]
In view of these findings concerning the water requirements of
crops, it cannot be far from the truth to say that, under average
cultural conditions, approximately 750 pounds of water are
required in an arid district for the production of one pound of
dry matter. Where the aridity is intense, this figure may be
somewhat low, and in localities of sub-humid conditions, it will
undoubtedly be too high. As a maximum average, however, for
districts interested in dry-farming, it can be used with safety.
Crop-producing power of rainfall
If this conclusion, that not more than 750 pounds of water are
required under ordinary dry-farm conditions for the production of
one pound of dry matter, be accepted, certain interesting
calculations can be made respecting the possibilities of
dry-farming. For example, the production of one bushel of wheat
will require 60 times 750, or 45,000 pounds of water. The wheat
kernels, however, cannot be produced without a certain amount of
straw, which under conditions of dry-farming seldom forms quite
one half of the weight of the whole plant. Let us say, however,
that the weights of straw and kernels are equal. Then, to produce
one bushel of wheat, with the corresponding quantity of straw,
would require 2 times 45,000, or 90,000 pounds of water. This is
equal to 45 tons of water for each bushel of wheat. While this is
a large figure, yet, in many localities, it is undoubtedly well
within the truth. In comparison with the amounts of water that
fall upon the land as rain, it does not seem extraordinarily
large.
One inch of water over one acre of land weighs approximately
226,875 pounds. or over 113 tons. If this quantity of water could
be stored in the soil and used wholly for plant production, it
would produce, at the rate of 45 tons of water for each bushel,
about 2-1/2 bushels of wheat. With 10 inches of rainfall, which up
to the present seems to be the lower limit of successful
dry-farming, there is a maximum possibility of producing 25
bushels of wheat annually.
In the subjoined table, constructed on the basis of the discussion
of this chapter, the wheat-producing powers of various degrees of
annual precipitation are shown:--
One acre inch of water will produce 2-1/2 bushels of wheat.
Ten acre inches of water will produce 25 bushels of wheat.
Fifteen acre inches of water will produce 37-1/2 bushels of wheat.
Twenty acre inches of water will produce 50 bushels of wheat.
It must be distinctly remembered, however, that under no known
system of tillage can all the water that falls upon a soil be
brought into the soil and stored there for plant use. Neither is
it possible to treat a soil so that all the stored soil-moisture
may be used for plant production. Some moisture, of necessity,
will evaporate directly from the soil, and some may be lost in
many other ways. Yet, even under a rainfall of 12 inches, if only
one half of the water can be conserved, which experiments have
shown to be very feasible, there is a possibility of producing 30
bushels of wheat per acre every other year, which insures an
excellent interest on the money and labor invested in the
production of the crop.
It is on the grounds outlined in this chapter that students of the
subject believe that ultimately large areas of the 'desert" may be
reclaimed by means of dry-farming. The real question before the
dry-farmer is not, "Is the rainfall sufficient?" but rather, "Is
it possible so to conserve and use the rainfall as to make it
available for the production of profitable crops?"
THE annual precipitation of rain and snow determines primarily the
location of dry-farm areas. As the rainfall varies, the methods of
dry-farming must be varied accordingly. Rainfall, alone, does not,
however, furnish a complete index of the crop-producing
possibilities of a country.
The distribution of the rainfall, the amount of snow, the
water-holding power of the soil, and the various
moisture-dissipating causes, such as winds, high temperature,
abundant sunshine, and low humidity frequently combine to offset
the benefits of a large annual precipitation. Nevertheless, no one
climatic feature represents, on the average, so correctly
dry-farming possibilities as does the annual rainfall. Experience
has already demonstrated that wherever the annual precipitation is
above 15 inches, there is no need of crop failures, if the soils
are suitable and the methods of dry-farming are correctly
employed. With an annual precipitation of 10 to 15 inches, there
need be very few failures, if proper cultural precautions are
taken. With our present methods, the areas that receive less than
10 inches of atmospheric precipitation per year are not safe for
dry-farm purposes. What the future will show in the reclamation of
these deserts, without irrigation, is yet conjectural.
Arid, semiarid, and sub-humid
Before proceeding to an examination of the areas in the United
States subject to the methods of dry-farming it may be well to
define somewhat more clearly the terms ordinarily used in the
description of the great territory involved in the discussion.
The states lying west of the 100th meridian are loosely spoken of
as arid, semiarid, or sub-humid states. For commercial purposes no
state wants to be classed as arid and to suffer under the handicap
of advertised aridity. The annual rainfall of these states ranges
from about 3 to over 30 inches.
In order to arrive at greater definiteness, it may be well to
assign definite rainfall values to the ordinarily used descriptive
terms of the region in question. It is proposed, therefore, that
districts receiving less than 10 inches of atmospheric
precipitation annually, be designated arid; those receiving
between 10 and 20 inches, semiarid; those receiving between 20 and
30 inches, sub-humid, and those receiving over 30 inches, humid.
It is admitted that even such a classification is arbitrary, since
aridity does not alone depend upon the rainfall, and even under
such a classification there is an unavoidable overlapping.
However, no one factor so fully represents varying degrees of
aridity as the annual precipitation, and there is a great need for
concise definitions of the terms used in describing the parts of
the country that come under dry-farming discussions. In this
volume, the terms "arid," "semiarid," "sub-humid" and "humid" are
used as above defined.
Precipitation over the dry-farm
territory
Nearly one half of the United States receives 20 inches or less
rainfall annually; and that when the strip receiving between 20
and 30 inches is added, the whole area directly subject to
reclamation by irrigation or dry-farming is considerably more than
one half (63 per cent) of the whole area of the United States.
Eighteen states are included in this area of low rainfall. The
areas of these, as given by the Census of 1900, grouped according
to the annual precipitation received, are shown below:-
Arid to Semi-arid Group
Total Area Land Surface (Sq. Miles)
Arizona 112,920
California 156,172
Colorado 103,645
Idaho 84,290
Nevada 109,740
Utah 82,190
Wyoming 97,545
TOTAL 746,532
Semiarid to Sub-Humid Group
Montana 145,310
Nebraska 76,840
New Mexico 112,460
North Dakota 70.195
Oregon 94,560
South Dakota 76,850
Washington 66,880
TOTAL 653,095
Sub-Humid to Humid Group
Kansas81,700
Minnesota79,205
Oklahoma38,830
Texas262,290
TOTAL462,025
GRAND TOTAL 1,861,652
The territory directly interested in the development of the
methods of dry-farming forms 63 per cent of the whole of the
continental United States, not including Alaska, and covers an
area of 1,861,652 square miles, or 1,191,457,280 acres. If any
excuse were needed for the lively interest taken in the subject of
dry-farming, it is amply furnished by these figures showing the
vast extent of the country interested in the reclamation of land
by the methods of dry-farming. As will be shown below, nearly
every other large country possesses similar immense areas under
limited rainfall.
Of the one billion, one hundred and ninety-one million, four
hundred and fifty-seven thousand, two hundred and eighty acres
(1,191,457,280) representing the dry-farm territory of the United
States, about 22 per cent, or a little more than one fifth, is
sub-humid and receives between 20 and 30 inches of rainfall,
annually; 61 per cent, or a little more than three fifths, is
semiarid and receives between 10 and 20 inches, annually, and
about 17 per cent, or a little less than one fifth, is arid and
receives less than 10 inches of rainfall, annually.
These calculations are based upon the published average rainfall
maps of the United States Weather Bureau. In the far West, and
especially over the so-called "desert" regions, with their sparse
population, meteorological stations are not numerous, nor is it
easy to secure accurate data from them. It is strongly probable
that as more stations are established, it will be found that the
area receiving less than 10 inches of rainfall annually is
considerably smaller than above estimated. In fact, the United
States Reclamation Service states that there are only 70,000,000
acres of desert-like land; that is, land which does not naturally
support plants suitable for forage. This area is about one third
of the lands which, so far as known, at present receive less than
10 inches of rainfall, or only about 6 per cent of the total
dry-farming territory.
In any case, the semiarid area is at present most vitally
interested in dry-farming. The sub-humid area need seldom suffer
from drouth, if ordinary well-known methods are employed; the arid
area, receiving less than 10 inches of rainfall, in all
probability, can be reclaimed without irrigation only by the
development of more suitable. methods than are known to-day. The
semiarid area, which is the special consideration of present-day
dry-farming represents an area of over 725,000,000 acres of land.
Moreover, it must be remarked that the full certainty of crops in
the sub-humid regions will come only with the adoption of
dry-farming methods; and that results already obtained on the edge
of the "deserts" lead to the belief that a large portion of the
area receiving less than 10 inches of rainfall, annually, will
ultimately be reclaimed without irrigation.
Naturally, not the whole of the vast area just discussed could be
brought under cultivation, even under the most favorable
conditions of rainfall. A very large portion of the territory in
question is mountainous and often of so rugged a nature that to
farm it would be an impossibility. It must not be forgotten,
however, that some of the best dry-farm lands of the West are
found in the small mountain valleys, which usually are pockets of
most fertile soil, under a good supply of rainfall. The foothills
of the mountains are almost invariably excellent dry-farm lands.
Newell estimates that 195,000,000 acres of land in the arid to
sub-humid sections are covered with a more or less dense growth of
timber. This timbered area roughly represents the mountainous and
therefore the nonarable portions of land. The same authority
estimates that the desert-like lands cover an area of 70,000,000
acres. Making the most liberal estimates for mountainous and
desert-like lands, at least one half of the whole area, or about
600,000,000 acres, is arable land which by proper methods may be
reclaimed for agricultural purposes. Irrigation when fully
developed may reclaim not to exceed 5 per cent of this area. From
any point of view, therefore, the possibilities involved in
dry-farming in the United States are immense.
Dry-farm area of the world
Dry-farming is a world problem. Aridity is a condition met and to
be overcome upon every continent. McColl estimates that in
Australia, which is somewhat larger than the continental United
States of America, only one third of the whole surface receives
above 20 inches of rainfall annually; one third receives from 10
to 20 inches, and one third receives less than l O inches. That
is, about 1,267,000,000 acres in Australia are subject to
reclamation by dry-farming methods. This condition is not far from
that which prevails in the United States, and is representative of
every continent of the world. The following table gives the
proportions of the earth's land surface under various degrees of
annual precipitations:--
| Annual Precipitation | Proportion of Earth's Land Surface |
| Under 10 inches | 25.0 per cent |
| From 10 to 20 inches | 30.0 per cent |
| From 20 to 40 inches | 20.0 per cent |
| From 40 to 60 inches | 11.0 per cent |
| From 60 to 80 inches | 9.0 per cent |
| From 100 to 120 inches | 4.0 per cent |
| From 120 to 160 inches | 0.5 per cent |
| Above 160 inches | 0.5 per cent |
|
Total |
100 per cent |
THE dry-farm territory of the United States stretches from the
Pacific seaboard to the 96th parallel of longitude, and from the
Canadian to the Mexican boundary, making a total area of nearly
1,800,000 square miles. This immense territory is far from being a
vast level plain. On the extreme east is the Great Plains region
of the Mississippi Valley which is a comparatively uniform country
of rolling hills, but no mountains. At a point about one third of
the whole distance westward the whole land is lifted skyward by
the Rocky Mountains, which cross the country from south to
northwest. Here are innumerable peaks, canons, high table-lands,
roaring torrents, and quiet mountain valleys. West of the Rockies
is the great depression known as the Great Basin, which has no
outlet to the ocean. It is essentially a gigantic level lake floor
traversed in many directions by mountain ranges that are offshoots
from the backbone of the Rockies. South of the Great Basin are the
high plateaus, into which many great chasms are cut, the best
known and largest of which is the great Canon of the Colorado.
North and east of the Great Basin is the Columbia River Basin
characterized by basaltic rolling plains and broken mountain
country. To the west, the floor of the Great Basin is lifted up
into the region of eternal snow by the Sierra Nevada Mountains,
which north of Nevada are known as the Cascades. On the west, the
Sierra Nevadas slope gently, through intervening valleys and minor
mountain ranges, into the Pacific Ocean. It would be difficult to
imagine a more diversified topography than is possessed by the
dry-farm territory of the United States.
Uniform climatic conditions are not to be expected over such a
broken country. The chief determining factors of
climate--latitude, relative distribution of land and water,
elevation, prevailing winds-- swing between such large extremes
that of necessity the climatic conditions of different sections
are widely divergent. Dry-farming is so intimately related to
climate that the typical climatic variations must be pointed out.
The total annual precipitation is directly influenced by the land
topography, especially by the great mountain ranges. On the east
of the Rocky Mountains is the sub-humid district, which receives
from 20 to 30 inches of rainfall annually; over the Rockies
themselves, semiarid conditions prevail; in the Great Basin,
hemmed in by the Rockies on the east and the Sierra Nevadas on the
west, more arid conditions predominate; to the west, over the
Sierras and down to the seacoast, semiarid to sub-humid conditions
are again found.
Seasonal distribution of rainfall
It is doubtless true that the total annual precipitation is the
chief factor in determining the success of dry-farming. However,
the distribution of the rainfall throughout the year is also of
great importance, and should be known by the farmer. A small
rainfall, coming at the most desirable season, will have greater
crop-producing power than a very much larger rainfall poorly
distributed. Moreover, the methods of tillage to be employed where
most of the precipitation comes in winter must be considerably
different from those used where the bulk of the precipitation
comes in the summer. The successful dry-farmer must know the
average annual precipitation, and also the average seasonal
distribution of the rainfall, over the land which he intends to
dry-farm before he can safely choose his cultural methods.
With reference to the monthly distribution of the precipitation
over the dry-farm territory of the United States, Henry of the
United States Weather Bureau recognizes five distinct types;
namely: (1) Pacific, (2) Sub-Pacific, (3) Arizona, (4) the
Northern Rocky Mountain and Eastern Foothills, and (5) the Plains
Type:--
"The Pacific Type.--This type is found in all of the
territory west of the Cascade and Sierra Nevada ranges, and also
obtains in a fringe of country to the eastward of the mountain
summits. The distinguishing characteristic of the Pacific type is
a wet season, extending from October to March, and a practically
rainless summer, except in northern California and parts of Oregon
and Washington. About half of the yearly precipitation comes in
the months of December, January, and February, the remaining half
being distributed throughout the seven months --September,
October, November, March, April, May, and June."
"Sub-Pacific Type.--The term 'Sub-Pacific' has been given
to that type of rainfall which obtains over eastern Washington,
Nevada, and Utah. The influences that control the precipitation of
this region are much similar to those that prevail west of the
Sierra Nevada and Cascade ranges. There is not, however, as in the
eastern type, a steady diminution in the precipitation with the
approach of spring, but rather a culmination in the
precipitation."
"Arizona Type.--The Arizona Type, so called because it is
more fully developed in that territory than elsewhere, prevails
over Arizona, New Mexico, and a small portion of eastern Utah and
Nevada. This type differs from all others in the fact that about
35 per cent of the rain falls in July and August. May and June are
generally the months of least rainfall."
"The Northern Rocky Mountain and Eastern Foothills Type.--This
type is closely allied to that of the plains to the eastward, and
the bulk of the rain falls in the foothills of the region in April
and May; in Montana, in May and June."
"The Plains Type.--This type embraces the greater part of
the Dakotas, Nebraska, Kansas; Oklahoma, the Panhandle of Texas,
and all the great corn and wheat states of the interior valleys.
This region is characterized by a scant winter precipitation over
the northern states and moderately heavy rains during the growing
season. The. bulk of the rains comes in May, June, and July."
This classification emphasizes the great variation in distribution
of rainfall over the dry-farm territory of the country. West of
the Rocky Mountains the precipitation comes chiefly in winter and
spring, leaving the summers rainless; while east of the Rockies,
the winters are somewhat rainless and the precipitation comes
chiefly in spring and summer. The Arizona type stands midway
between these types. This variation in the distribution of the
rainfall requires that different methods be employed in storing
and conserving the rainfall for crop production. The adaptation of
cultural methods to the seasonal distribution of rainfall will be
discussed hereafter.
Snowfall
Closely related to the distribution of the rainfall and the
average annual temperature is the snowfall. Wherever a relatively
large winter precipitation occurs, the dry-farmer is benefited if
it comes in the form of snow. The fall-planted seeds are better
protected by the snow; the evaporation is lower and it appears
that the soil is improved by the annual covering of snow. In any
case, the methods of culture are in a measure dependent upon the
amount of snowfall and the length of time that it lies upon the
ground.
Snow falls over most of the dry-farm territory, excepting the
lowlands of California, the immediate Pacific coast, and other
districts where the average annual temperature is high. The
heaviest snowfall is in the intermountain district, from the west
slope of the Sierra Nevadas to the east slope of the Rockies. The
degree of snowfall on the agricultural lands is very variable and
dependent upon local conditions. Snow falls upon all the high
mountain ranges.
Temperature
With the exceptions of portions of California, Arizona, and Texas
the average annual surface temperature of the dry-farm territory
of the United States ranges from 40° to 55° F. The average is not
far from 45° F. This places most of the dry-farm territory in the
class of cold regions, though a small area on the extreme east
border may be classed as temperate, and parts of California and
Arizona as warm. The range in temperature from the highest in
summer to the lowest in winter is considerable, but not widely
different from other similar parts of the United States. The range
is greatest in the interior mountainous districts, and lowest
along the seacoast. The daily range of the highest and lowest
temperatures for any one day is generally higher over dry-farm
sections than over humid districts. In the Plateau regions of the
semiarid country the average daily variation is from 30 to 35° F.,
while east of the Mississippi it is only about 20° F. This greater
daily range is chiefly due to the clear skies and scant vegetation
which facilitate excessive warming by day and cooling by night.
The important temperature question for the dry-farmer is whether
the growing season is sufficiently warm and long to permit the
maturing of crops. There are few places, even at high altitudes in
the region considered, where the summer temperature is so low as
to retard the growth of plants. Likewise, the first and last
killing frosts are ordinarily so far apart as to allow an ample
growing season. It must be remembered that frosts are governed
very largely by local topographic features, and must be known from
a local point of view. It is a general law that frosts are more
likely to occur in valleys than on hillsides, owing to the
downward drainage of the cooled air. Further, the danger of frost
increases with the altitude. In general, the last killing frost in
spring over the dry-farm territory varies from March 15 to May 29,
and the first killing frost in autumn from September 15 to
November 15. These limits permit of the maturing of all ordinary
farm crops, especially the grain crops.
Relative humidity
At a definite temperature, the atmosphere can hold only a certain
amount of water vapor. When the air can hold no more, it is said
to be saturated. When it is not saturated, the amount of water
vapor actually held by the air is expressed in percentages of the
quantity required for saturation. A relative humidity of 100 per
cent means that the air is saturated; of 50 per cent, that it is
only one half saturated. The drier the air is, the more rapidly
does the water evaporate into it. To the dry-farmer, therefore,
the relative humidity or degree of dryness of the air is of very
great importance. According to Professor Henry, the chief
characteristics of the geographic distribution of relative
humidity in the United States are as follows:--
(1) Along the coasts there is a belt of high humidity at all
seasons, the percentage of saturation ranging from 75 to 80 per
cent.
(2) Inland, from about the 70th meridian eastward to the Atlantic
coast, the amount varies between 70 and 75 per cent.
(3) The dry region is in the Southwest, where the average annual
value is not over 50 per cent. In this region are included
Arizona, New Mexico, western Colorado, and the greater portion of
both Utah and Nevada. The amount of annual relative humidity in
the remaining portion of the elevated district, between the 100th
meridian on the east to the Sierra Nevada and the Cascades on the
west, varies between 55 and 65 per cent. In July, August, and
September, the mean values in the Southwest sink as low as 20 to
30 per cent, while along the Pacific coast districts they continue
about 80 per cent the year round. In the Atlantic coast districts,
and generally east from the Mississippi River, the variation from
month to month is not great. April is probably the driest month of
the year.
The air of the dry-farm territory, therefore, on the whole,
contains considerably less than two thirds the amount of moisture
carried by the air of the humid states. This means that
evaporation from plant leaves and soil surfaces will go on more
rapidly in semiarid than in humid regions. Against this danger,
which cannot he controlled, the dry-farmer must take special
precautions.
Sunshine
The amount of sunshine in a dry-farm section is also of
importance. Direct sunshine promotes plant growth, but at the same
time it accelerates the evaporation of water from the soil. The
whole dry-farm territory receives more sunshine than do the humid
sections. In fact, the amount of sunshine may roughly be said to
increase as the annual rainfall decreases. Over the larger part of
the arid and semiarid sections the sun shines over 70 per cent of
the time.
Winds
The winds of any locality, owing to their moisture- dissipating
power play an important part in the success of dry-farming. A
persistent wind will offset much of the benefit of a heavy
rainfall and careful cultivation. While great general laws have
been formulated regarding the movements of the atmosphere, they
are of minor value in judging the effect of wind on any farming
district. Local observations, however, may enable the farmer to
estimate the probable effect of the winds and thus to formulate
proper cultural means of protection. In general, those living in a
district are able to describe it without special observations as
windy or quiet. In the dry-farm territory of the United States the
one great region of relatively high and persistent winds is the
Great Plains region east of the Rocky Mountains. Dry-farmers in
that section will of necessity be obliged to adopt cultural
methods that will prevent the excessive evaporation naturally
induced by the unhindered wind, and the possible blowing of
well-tilled fallow land.
Summary
The dry-farm territory is characterized by a low rainfall,
averaging between 10 and 20 inches, the distribution of which
falls into two distinct types: a heavy winter and spring with a
light summer precipitation, and a heavy spring and summer with a
light winter precipitation. Snow falls over most of the territory,
but does not lie long outside of the mountain states. The whole
dry-farm territory may be classed as temperate to cold; relatively
high and persistent winds blow only over the Great Plains, though
local conditions cause strong regular winds in many other places;
the air is dry and the sunshine is very abundant. In brief, little
water falls upon the dry-farm territory, and the climatic factors
are of a nature to cause rapid evaporation.
In view of this knowledge, it is not surprising that thousands of
farmers, employing, often carelessly agricultural methods
developed in humid sections, have found only hardships and poverty
on the present dry-farm empire of the United States.
Drouth
Drouth is said to be the arch enemy of the dry-farmer, but few
agree upon its meaning. For the purposes of this volume, drouth
may be defined as a condition under which crops fail to mature
because of an insufficient supply of water. Providence has
generally been charged with causing drouths, but under the above
definition, man is usually the cause. Occasionally, relatively dry
years occur, but they are seldom dry enough to cause crop failures
if proper methods of farming have been practiced. There are four
chief causes of drouth: (1) Improper or careless preparation of
the soil; (2) failure to store the natural precipitation in the
soil; (3) failure to apply proper cultural methods for keeping the
moisture in the soil until needed by plants, and (4) sowing too
much seed for the available soil-moisture.
Crop failures due to untimely frosts, blizzards, cyclones,
tornadoes, or hail may perhaps be charged to Providence, but the
dry-farmer must accept the responsibility for any crop injury
resulting from drouth. A fairly accurate knowledge of the climatic
conditions of the district, a good understanding of the principles
of agriculture without irrigation under a low rainfall, and a
vigorous application of these principles as adapted to the local
climatic conditions will make dry-farm failures a rarity.
IMPORTANT as is the rainfall in making dry-farming successful, it
is not more so than the soils of the dry-farms. On a shallow soil,
or on one penetrated with gravel streaks, crop failures are
probable even under a large rainfall; but a deep soil of uniform
texture, unbroken by gravel or hardpan, in which much water may be
stored, and which furnishes also an abundance of feeding space for
the roots, will yield large crops even under a very small
rainfall. Likewise, an infertile soil, though it be deep, and
under a large precipitation, cannot be depended on for good crops;
but a fertile soil, though not quite so deep, nor under so large a
rainfall, will almost invariably bring large crops to maturity.
A correct understanding of the soil, from the surface to a depth
of ten feet, is almost indispensable before a safe Judgment can be
pronounced upon the full dry-farm possibilities of a district.
Especially is it necessary to know (a) the depth, (b) the
uniformity of structure, and (c) the relative fertility of the
soil, in order to plan an intelligent system of farming that will
be rationally adapted to the rainfall and other climatic factors.
It is a matter of regret that so much of our information
concerning the soils of the dry-farm territory of the United
States and other countries has been obtained according to the
methods and for the needs of humid countries, and that, therefore,
the special knowledge of our arid and semiarid soils needed for
the development of dry-farming is small and fragmentary. What is
known to-day concerning the nature of arid soils and their
relation to cultural processes under a scanty rainfall is due very
largely to the extensive researches and voluminous writings of Dr.
E. W. Hilgard, who for a generation was in charge of the
agricultural work of the state of California. Future students of
arid soils must of necessity rest their investigations upon the
pioneer work done by Dr. Hilgard. The contents of this chapter are
in a large part gathered from Hilgard's writings.
The formation of soils
"Soil is the more or less loose and friable material in which, by
means of their roots, plants may or do find a foothold and
nourishment, as well as other conditions of growth." Soil is
formed by a complex process, broadly known as weathering, from
the rocks which constitute the earth's crust. Soil is in fact only
pulverized and altered rock. The forces that produce soil from
rocks are of two distinct classes, physical and chemical. The
physical agencies of soil production merely cause a pulverization
of the rock; the chemical agencies, on the other hand, so
thoroughly change the essential nature of the soil particles that
they are no longer like the rock from which they were formed.
Of the physical agencies, temperature changes are first
in order of time, and perhaps of first importance. As the heat of
the day increases, the rock expands, and as the cold night
approaches, contracts. This alternate expansion and contraction,
in time, cracks the surfaces of the rocks. Into the tiny crevices
thus formed water enters from the falling snow or rain. When
winter comes, the water in these cracks freezes to ice, and in so
doing expands and widens each of the cracks. As these processes
are repeated from day to day, from year to year, and from
generation to generation, the surfaces of the rocks crumble. The
smaller rocks so formed are acted upon by the same agencies, in
the same manner, and thus the process of pulverization goes on.
It is clear, then, that the second great agency of soil formation,
which always acts in conjunction with temperature changes, is freezing
water. The rock particles formed in this manner are often
washed down into the mountain valleys, there caught by great
rivers, ground into finer dust, and at length deposited in the
lower valleys. Moving water thus becomes another physical
agency of soil production. Most of the soils covering the great
dry-farm territory of the United States and other countries have
been formed in this way.
In places, glaciers moving slowly down the canons crush and grind
into powder the rock over which they pass and deposit it lower
down as soils. In other places, where strong winds blow with
frequent regularity, sharp soil grains are picked up by the air
and hurled against the rocks, which, under this action, are carved
into fantastic forms. In still other places, the strong winds
carry soil over long distances to be mixed with other soils.
Finally, on the seashore the great waves dashing against the rocks
of the coast line, and rolling the mass of pebbles back and forth,
break and pulverize the rock until soil is formed. Glaciers,
winds, and waves are also, therefore, physical
agencies of soil formation.
It may be noted that the result of the action of all these
agencies is to form a rock powder, each particle of which
preserves the composition that it had while it was a constituent
part of the rock. It may further be noted that the chief of these
soil-forming agencies act more vigorously in arid than in humid
sections. Under the cloudless sky and dry atmosphere of regions of
limited rainfall, the daily and seasonal temperature changes are
much greater than in sections of greater rainfall. Consequently
the pulverization of rocks goes on most rapidly in dry-farm
districts. Constant heavy winds, which as soil formers are second
only to temperature changes and freezing water, are also usually
more common in arid than in humid countries. This is strikingly
shown, for instance, on the Colorado desert and the Great Plains.
The rock powder formed by the processes above described is
continually being acted upon by agencies, the effect of which is
to change its chemical composition. Chief of these agencies is water,
which exerts a solvent action on all known substances. Pure
water exerts a strong solvent action, but when it has been
rendered impure by a variety of substances, naturally occurring,
its solvent action is greatly increased.
The most effective water impurity, considering soil formation, is
the gas, carbon dioxid. This gas is formed whenever plant
or animal substances decay, and is therefore found, normally, in
the atmosphere and in soils. Rains or flowing water gather the
carbon dioxid from the atmosphere and the soil; few natural waters
are free from it. The hardest rock particles are disintegrated by
carbonated water, while limestones, or rocks containing lime, are
readily dissolved.
The result of the action of carbonated water upon soil particles
is to render soluble, and therefore more available to plants, many
of the important plant-foods. In this way the action of water,
holding in solution carbon dioxid and other substances, tends to
make the soil more fertile.
The second great chemical agency of soil formation is the oxygen
of the air. Oxidation is a process of more or less rapid burning,
which tends to accelerate the disintegration of rocks.
Finally, the plants growing in soils are powerful agents
of soil formation. First, the roots forcing their way into the
soil exert a strong pressure which helps to pulverize the soil
grains; secondly, the acids of the plant roots actually dissolve
the soil, and third, in the mass of decaying plants, substances
are formed, among them carbon dioxid, that have the power of
making soils more soluble.
It may be noted that moisture, carbon dioxid, and vegetation, the
three chief agents inducing chemical changes in soils, are most
active in humid districts. While, therefore, the physical agencies
of soil formation are most active in arid climates, the same
cannot be said of the chemical agencies. However, whether in arid
or humid climates, the processes of soil formation, above
outlined, are essentially those of the "fallow" or resting-period
given to dry-farm lands. The fallow lasts for a few months or a
year, while the process of soil formation is always going on and
has gone on for ages; the result, in quality though not in
quantity, is the same--the rock particles are pulverized and the
plant-foods are liberated. It must be remembered in this
connection that climatic differences may and usually do influence
materially the character of soils formed from one and the same
kind of rock.
Characteristics of arid soils
The net result of the processes above described Is a rock powder
containing a great variety of sizes of soil grains intermingled
with clay. The larger soil grains are called sand; the smaller,
silt, and those that are so small that they do not settle from
quiet water after 24 hours are known as clay.
Clay differs materially from sand and silt, not only in size of
particles, but also in properties and formation. It is said that
clay particles reach a degree of fineness equal to 1/2500 of an
inch. Clay itself, when wet and kneaded, becomes plastic and
adhesive and is thus easily distinguished from sand. Because of
these properties, clay is of great value in holding together the
larger soil grains in relatively large aggregates which give soils
the desired degree of filth. Moreover, clay is very retentive of
water, gases, and soluble plant-foods, which are important factors
in successful agriculture. Soils, in fact, are classified
according to the amount of clay that they contain. Hilgard
suggests the following classification:--
Very sandy soils0.5 to 3 per cent clay
Ordinary sandy soils3.0 to 10 per cent clay
Sandy loams10.0 to 15 per cent clay
Clay loams15.0 to 25 per cent clay
Clay soils25.0 to 35 per cent clay
Heavy clay soils35.0 per cent and over
Clay may be formed from any rock containing some form of combined
silica (quartz). Thus, granites and crystalline rocks
generally, volcanic rocks, and shales will produce clay if
subjected to the proper climatic conditions. In the formation of
clay, the extremely fine soil particles are attacked by the soil
water and subjected to deep-going chemical changes. In fact, clay
represents the most finely pulverized and most highly decomposed
and hence in a measure the most valuable portion of the soil. In
the formation of clay, water is the most active agent, and under
humid conditions its formation is most rapid.
It follows that dry-farm soils formed under a more or less
rainless climate contain less clay than do humid soils. This
difference is characteristic, and accounts for the statement
frequently made that heavy clay soils are not the best for
dry-farm purposes. The fact is, that heavy clay soils are very
rare in arid regions; if found at all, they have probably been
formed under abnormal conditions, as in high mountain valleys, or
under prehistoric humid climates.
Sand.--The sand-forming rocks that are not capable of clay
production usually consist of uncombined silica or
quartz, which when pulverized by the soil-forming agencies give a
comparatively barren soil. Thus it has come about that ordinarily
a clayey soil is considered "strong" and a sandy soil "weak."
Though this distinction is true in humid climates where clay
formation is rapid, it is not true in arid climates, where true
clay is formed very slowly. Under conditions of deficient
rainfall, soils are naturally less clayey, but as the sand and
silt particles are produced from rocks which under humid
conditions would yield clay, arid soils are not necessarily less
fertile.
Experiment has shown that the fertility in the sandy soils of arid
sections is as large and as available to plants as in the clayey
soils of humid regions. Experience in the arid section of America,
in Egypt, India, and other desert-like regions has further proved
that the sands of the deserts produce excellent crops whenever
water is applied to them. The prospective dry-farmer, therefore,
need not be afraid of a somewhat sandy soil, provided it has been
formed under arid conditions. In truth, a degree of sandiness is
characteristic of dry-farm soils.
The humus content forms another characteristic difference
between arid and humid soils. In humid regions plants cover the
soil thickly; in arid regions they are bunched scantily over the
surface; in the former case the decayed remnants of generations of
plants form a large percentage of humus in the upper soil; in the
latter, the scarcity of plant life makes the humus content low.
Further, under an abundant rainfall the organic matter in the soil
rots slowly; whereas in dry warm climates the decay is very
complete. The prevailing forces in all countries of deficient
rainfall therefore tend to yield soils low in humus.
While the total amount of humus in arid soils is very much lower
than in humid soils, repeated investigation has shown that it
contains about 3-1/2 times more nitrogen than is found in humus
formed under an abundant rainfall. Owing to the prevailing
sandiness of dry-farm soils, humus is not needed so much to give
the proper filth to the soil as in the humid countries where the
content of clay is so much higher. Since, for dry-farm purposes,
the nitrogen content is the most important quality of the humus,
the difference between arid and humid soils, based upon the humus
content, is not so great as would appear at first sight.
Soil and subsoil.--In countries of abundant rainfall, a
great distinction exists between the soil and the subsoil. The
soil is represented by the upper few inches which are filled with
the remnants of decayed vegetable matter and modified by plowing,
harrowing, and other cultural operations. The subsoil has been
profoundly modified by the action of the heavy rainfall, which, in
soaking through the soil, has carried with it the finest soil
grains, especially the clay, into the lower soil layers.
In time, the subsoil has become more distinctly clayey than the
topsoil. Lime and other soil ingredients have likewise been
carried down by the rains and deposited at different depths in the
soil or wholly washed away. Ultimately, this results in the
removal from the topsoil of the necessary plant-foods and the
accumulation in the subsoil of the fine clay particles which so
compact the subsoil as to make it difficult for roots and even air
to penetrate it. The normal process of weathering or soil
disintegration will then go on most actively in the topsoil and
the subsoil will remain unweathered and raw. This accounts for the
well-known fact that in humid countries any subsoil that may have
been plowed up is reduced to a normal state of fertility and crop
production only after several years of exposure to the elements.
The humid farmer, knowing this, is usually very careful not to let
his plow enter the subsoil to any great depth.
In the arid regions or wherever a deficient rainfall prevails,
these conditions are entirely reversed. The light rainfall seldom
completely fills the soil pores to any considerable depth, but it
rather moves down slowly as a him, enveloping the soil grains. The
soluble materials of the soil are, in part at least, dissolved and
carried down to the lower limit of the rain penetration, but the
clay and other fine soil particles are not moved downward to any
great extent. These conditions leave the soil and subsoil of
approximately equal porosity. Plant roots can then penetrate the
soil deeply, and the air can move up and down through the soil
mass freely and to considerable depths. As a result, arid soils
are weathered and made suitable for plant nutrition to very great
depths. In fact, in dry-farm regions there need be little talk
about soil and subsoil, since the soil is uniform in texture and
usually nearly so in composition, from the top down to a distance
of many feet.
Many soil sections 50 or more feet in depth are exposed in the
dry-farming territory of the United States, and it has often been
demonstrated that the subsoil to any depth is capable of
producing, without further weathering, excellent yields of crops.
This granular, permeable structure, characteristic of arid soils,
is perhaps the most important single quality resulting from rock
disintegration under arid conditions. As Hilgard remarks, it would
seem that the farmer in the arid region owns from three to four
farms, one above the other, as compared with the same acreage in
the eastern states.
This condition is of the greatest importance in developing the
principles upon which successful dry-farming rests. Further, it
may be said that while in the humid East the farmer must be
extremely careful not to turn up with his plow too much of the
inert subsoil, no such fear need possess the western farmer. On
the contrary, he should use his utmost endeavor to plow as deeply
as possible in order to prepare the very best reservoir for the
falling waters and a place for the development of plant roots.
Gravel seams.--It need be said, however, that in a number
of localities in the dry-farm territory the soils have been
deposited by the action of running water in such a way that the
otherwise uniform structure of the soil is broken by occasional
layers of loose gravel. While this is not a very serious obstacle
to the downward penetration of roots, it is very serious in
dry-farming, since any break in the continuity of the soil mass
prevents the upward movement of water stored in the lower soil
depths. The dry-farmer should investigate the soil which he
intends to use to a depth of at least 8 to 10 feet to make sure,
first of all, that he has a continuous soil mass, not too clayey
in the lower depths, nor broken by deposits of gravel.
Hardpan.--Instead of the heavy clay subsoil of humid
regions, the so-called hardpan occurs in regions of limited
rainfall. The annual rainfall, which is approximately constant,
penetrates from year to year very nearly to the same depth. Some
of the lime found so abundantly in arid soils is dissolved and
worked down yearly to the lower limit of the rainfall and left
there to enter into combination with other soil ingredients.
Continued through long periods of time this results in the
formation of a layer of calcareous material at the average depth
to which the rainfall has penetrated the soil. Not only is the
lime thus carried down, but the finer particles are carried down
in like manner. Especially where the soil is poor in lime is the
clay worked down to form a somewhat clayey hardpan. A hardpan
formed in such a manner is frequently a serious obstacle to the
downward movement of the roots, and also prevents the annual
precipitation from moving down far enough to be beyond the
influence of the sunshine and winds. It is fortunate, however,
that in the great majority of instances this hardpan gradually
disappears under the influence of proper methods of dry-farm
tillage. Deep plowing and proper tillage, which allow the rain
waters to penetrate the soil, gradually break up and destroy the
hardpan, even when it is 10 feet below the surface. Nevertheless,
the farmer should make sure whether or not the hardpan does exist
in the soil and plan his methods accordingly. If a hardpan is
present, the land must be fallowed more carefully every other
year, so that a large quantity of water may be stored in the soil
to open and destroy the hardpan.
Of course, in arid as in humid countries, it often happens that a
soil is underlaid, more or less near the surface, by layers of
rock, marl deposits, and similar impervious or hurtful substances.
Such deposits are not to be classed with the hardpans that occur
normally wherever the rainfall is small.
Leaching.--Fully as important as any of the differences
above outlined are those which depend definitely upon the leaching
power of a heavy rainfall. In countries where the rainfall is 30
inches or over, and in many places where the rainfall is
considerably less, the water drains through the soil into the
standing ground water. There is, therefore, in humid countries, a
continuous drainage through the soil after every rain, and in
general there is a steady downward movement of soil-water
throughout the year. As is clearly shown by the appearance, taste,
and chemical composition of drainage waters, this process leaches
out considerable quantities of the soluble constituents of the
soil.
When the soil contains decomposing organic matter, such as roots,
leaves, stalks, the gas carbon dioxid is formed, which, when
dissolved in water, forms a solution of great solvent power. Water
passing through well-cultivated soils containing much humus
leaches out very much more material than pure water could do. A
study of the composition of the drainage waters from soils and the
waters of the great rivers shows that immense quantities of
soluble soil constituents are taken out of the soil in countries
of abundant rainfall. These materials ultimately reach the ocean,
where they are and have been concentrated throughout the ages. In
short, the saltiness of the ocean is due to the substances that
have been washed from the soils in countries of abundant rainfall.
In arid regions, on the other hand, the rainfall penetrates the
soil only a few feet. In time, it is returned to the surface by
the action of plants or sunshine and evaporated into the air. It
is true that under proper methods of tillage even the light
rainfall of arid and semiarid regions may he made to pass to
considerable soil depths, yet there is little if any drainage of
water through the soil into the standing ground water. The arid
regions of the world, therefore, contribute proportionately a
small amount of the substances which make up the salt of the sea.
Alkali soils.--Under favorable conditions it sometimes
happens that the soluble materials, which would normally be washed
out of humid soils, accumulate to so large a degree in arid soils
as to make the lands unfitted for agricultural purposes. Such
lands are called alkali lands. Unwise irrigation in arid climates
frequently produces alkali spots, but many occur naturally. Such
soils should not be chosen for dry-farm purposes, for they are
likely to give trouble.
Plant-food content.--This condition necessarily leads at
once to the suggestion that the soils from the two regions must
differ greatly in their fertility or power to produce and sustain
plant life. It cannot be believed that the water-washed soils of
the East retain as much fertility as the dry soils of the West.
Hilgard has made a long and elaborate study of this somewhat
difficult question and has constructed a table showing the
composition of typical soils of representative states in the arid
and humid regions. The following table shows a few of the average
results obtained by him:--
| Source of soil | Number of samples analyzed | Insoluble residue | Soluble silica | Alumina | Lime | Potash | Phos. Acid |
Humus |
| Humid | 696 | 84.17 | 4.04 | 3.66 | 0.13 | 0.21 | 0.12 | 1.22 |
| Arid | 573 | 69.16 | 6.71 | 7.61 | 1.43 | 0.67 | 0.16 | 1.13 |
THE great depth and high fertility of the soils of arid and
semiarid regions have made possible the profitable production of
agricultural plants under a rainfall very much lower than that of
humid regions. To make the principles of this system fully
understood, it is necessary to review briefly our knowledge of the
root systems of plants growing under arid conditions.
Functions of roots
The roots serve at least three distinct uses or purposes: First,
they give the plant a foothold in the earth; secondly, they enable
the plant to secure from the soil the large amount of water needed
in plant growth, and, thirdly, they enable the plant to secure the
indispensable mineral foods which can be obtained only from the
soil. So important is the proper supply of water and food in the
growth of a plant that, in a given soil, the crop yield is usually
in direct proportion to the development of the root system.
Whenever the roots are hindered in their development, the growth
of the plant above ground is likewise retarded, and crop failure
may result. The importance of roots is not fully appreciated
because they are hidden from direct view. Successful dry-farming
consists, largely in the adoption of practices that facilitate a
full and free development-of plant roots. Were it not that the
nature of arid soils, as explained in preceding chapters, is such
that full root development is comparatively easy, it would
probably be useless to attempt to establish a system of
dry-farming.
Kinds of roots
The root is the part of the plant that is found underground. It
has numerous branches, twigs, and filaments. The root which first
forms when the seed bursts is known as the primary root. From this
primary root other roots develop, which are known as secondary
roots. When the primary root grows more rapidly than the secondary
roots, the so-called taproot, characteristic of lucerne, clover,
and similar plants, is formed. When, on the other hand, the
taproot grows slowly or ceases its growth, and the numerous
secondary roots grow long, a fibrous root system results, which is
characteristic of the cereals, grasses, corn, and other similar
plants. With any type of root, the tendency of growth is downward;
though under conditions that are not favorable for the downward
penetration of the roots the lateral extensions may be very large
and near the surface
Photo : Wheat RootsAlfalfa Roots
Extent of
roots
A number of investigators have attempted to determine the weight
of the roots as compared with the weight of the plant above
ground, hut the subject, because of its great experimental
difficulties, has not been very accurately explained. Schumacher,
experimenting about 1867, found that the roots of a
well-established field of clover weighed as much as the total
weight of the stems and leaves of the year's crop, and that the
weight of roots of an oat crop was 43 per cent of the total weight
of seed and straw. Nobbe, a few years later, found in one of his
experiments that the roots of timothy weighed 31 per cent of the
weight of the hay. Hosaeus, investigating the same subject about
the same time, found that the weight of roots of one of the brome
grasses was as great as the weight of the part above ground; of
serradella, 77 per cent; of flax, 34 per cent; of oats, 14 per
cent; of barley, 13 per cent, and of peas, 9 per cent. Sanborn,
working at the Utah Station in 1893, found results very much the
same
Although these results are not concordant, they show that the
weight of the roots is considerable, in many cases far beyond the
belief of those who have given the subject little or no attention.
It may be noted that on the basis of the figures above obtained,
it is very probable that the roots in one acre of an average wheat
crop would weigh in the neighborhood of a thousand
pounds--possibly considerably more. It should be remembered that
the investigations which yielded the preceding results were all
conducted in humid climates and at a time when the methods for the
study of the root systems were poorly developed. The data
obtained, therefore, represent, in all probability, minimum
results which would be materially increased should the work be
repeated now.
The relative weights of the roots and the stems and the leaves do
not alone show the large quantity of roots; the total lengths of
the roots are even more striking. The German investigator, Nobbe,
in a laborious experiment conducted about 1867, added the lengths
of all the fine roots from each of various plants. He found that
the total length of roots, that is, the sum of the lengths of all
the roots, of one wheat plant was about 268 feet, and that the
total length of the roots of one plant of rye was about 385 feet.
King, of Wisconsin, estimates that in one of his experiments, one
corn plant produced in the upper 3 feet of soil 1452 feet of
roots. These surprisingly large numbers indicate with emphasis the
thoroughness with which the roots invade the soil.
Depth of root penetration
The earlier root studies did not pretend to determine the depth to
which roots actually penetrate the earth. In recent years,
however, a number of carefully conducted experiments were made by
the New York, Wisconsin, Minnesota, Kansas, Colorado, and
especially the North Dakota stations to obtain accurate
information concerning the depth to which agricultural plants
penetrate soils. It is somewhat regrettable, for the purpose of
dry-farming, that these states, with the exception of Colorado,
are all in the humid or sub-humid area of the United States.
Nevertheless, the conclusions drawn from the work are such that
they may be safely applied in the development of the principles of
dry-farming.
There is a general belief among farmers that the roots of all
cultivated crops are very near the surface and that few reach a
greater depth than one or two feet. The first striking result of
the American investigations was that every crop, without
exception, penetrates the soil deeper than was thought possible in
earlier days. For example, it was found that corn roots penetrated
fully four feet into the ground and that they fully occupied all
of the soil to that depth.
On deeper and somewhat drier soils, corn roots went down as far as
eight feet. The roots of the small grains,--wheat, oats,
barley,--penetrated the soil from four to eight or ten feet.
Various perennial grasses rooted to a depth of four feet the first
year; the next year, five and one half feet; no determinations
were made of the depth of the roots in later years, though it had
undoubtedly increased. Alfalfa was the deepest rooted of all the
crops studied by the American stations. Potato roots filled the
soil fully to a depth of three feet; sugar beets to a depth of
nearly four feet.
In every case, under conditions
prevailing in the experiments, and which did not have in mind the
forcing of the roots down to extraordinary depths, it seemed that
the normal depth of the roots of ordinary field crops was from
three to eight feet. Sub-soiling and deep plowing enable the roots
to go deeper into the soil. This work has been confirmed in
ordinary experience until there can be little question about the
accuracy of the results.
Almost all of these results were obtained in humid climates on
humid soils, somewhat shallow, and underlain by a more or less
infertile subsoil. In fact, they were obtained under conditions
really unfavorable to plant growth. It has been explained in
Chapter V that soils formed under arid or semiarid conditions are
uniformly deep and porous and that the fertility of the subsoil
is, in most cases, practically as great as of the topsoil. There
is, therefore, in arid soils, an excellent opportunity for a
comparatively easy penetration of the roots to great depths and,
because of the available fertility, a chance throughout the whole
of the subsoil for ample root development. Moreover, the porous
condition of the soil permits the entrance of air, which helps to
purify the soil atmosphere and thereby to make the conditions more
favorable for root development. Consequently it is to be expected
that, in arid regions, roots will ordinarily go to a much greater
depth than in humid regions.
It is further to be remembered that roots are in constant search
of food and water and are likely to develop in the directions
where there is the greatest abundance of these materials. Under
systems of dry-farming the soil water is stored more or less
uniformly to considerable depths--ten feet or more --and in most
cases the percentage of moisture in the spring and summer is as
large or larger some feet below the surface than in the upper two
feet. The tendency of the root is, then, to move downward to
depths where there is a larger supply of water. Especially is this
tendency increased by the available soil fertility found
throughout the whole depth of the soil mass.
It has been argued that in many of the irrigated sections the
roots do not penetrate the soil to great depths. This is true,
because by the present wasteful methods of irrigation the plant
receives so much water at such untimely seasons that the roots
acquire the habit of feeding very near the surface where the water
is so lavishly applied. This means not only that the plant suffers
more greatly in times of drouth, but that, since the feeding
ground of the roots is smaller, the crop is likely to be small.
These deductions as to the depth to which plant roots will
penetrate the soil in arid regions are fully corroborated by
experiments and general observation. The workers of the Utah
Station have repeatedly observed plant roots on dry-farms to a
depth of ten feet. Lucerne roots from thirty to fifty feet in
length are frequently exposed in the gullies formed by the
mountain torrents. Roots of trees, similarly, go down to great
depths. Hilgard observes that he has found roots of grapevines at
a depth of twenty-two feet below the surface, and quotes Aughey as
having found roots of the native Shepherdia in Nebraska to a depth
of fifty feet. Hilgard further declares that in California
fibrous-rooted plants, such as wheat and barley, may descend in
sandy soils from four to seven feet. Orchard trees in the arid
West, grown properly, are similarly observed to send their roots
down to great depths. In fact, it has become a custom in many arid
regions where the soils are easily penetrable to say that the root
system of a tree corresponds in extent and branching to the part
of the tree above ground.
Now, it is to be observed that, generally, plants grown in dry
climates send their roots straight down into the soil; whereas in
humid climates, where the topsoil is quite moist and the subsoil
is hard, roots branch out laterally and fill the upper foot or two
of the soil. A great deal has been said and written about the
danger of deep cultivation, because it tends to injure the roots
that feed near the surface. However true this may be in humid
countries, it is not vital in the districts primarily interested
in dry-farming; and it is doubtful if the objection is as valid in
humid countries as is often declared. True, deep cultivation,
especially when performed near the plant or tree, destroys the
surface-feeding roots, but this only tends to compel the deeper
lying roots to make better use of the subsoil.
When, as in arid regions, the subsoil is fertile and furnishes a
sufficient amount of water, destroying the surface roots is no
handicap whatever. On the contrary, in times of drouth, the
deep-lying roots feed and drink at their leisure far from the hot
sun or withering winds, and the plants survive and arrive at rich
maturity, while the plants with shallow roots wither and die or
are so seriously injured as to produce an inferior crop.
Therefore, in the system of dry-farming as developed in this
volume, it must be understood that so far as the farmer has power,
the roots must be driven downward into the soil, and that no
injury needs to be apprehended from deep and vigorous cultivation.
One of the chief attempts of the dry-farmer must be to see to it
that the plants root deeply. This can be done only by preparing
the right kind of seed-bed and by having the soil in its lower
depths well-stored with moisture, so that the plants may be
invited to descend. For that reason, an excess of moisture in the
upper soil when the young plants are rooting is really an injury
to them.
THE large amount of water required for the production of plant
substance is taken from the soil by the roots. Leaves and stems do
not absorb appreciable quantities of water. The scanty rainfall of
dry-farm districts or the more abundant precipitation of humid
regions must, therefore, be made to enter the soil in such a
manner as to be readily available as soil-moisture to the roots at
the right periods of plant growth.
In humid countries, the rain that falls during the growing season
is looked upon, and very properly, as the really effective factor
in the production of large crops. The root systems of plants grown
under such humid conditions are near the surface, ready to absorb
immediately the rains that fall, even if they do not soak deeply
into the soil. As has been shown in Chapter IV, it is only over a
small portion of the dry-farm territory that the bulk of the
scanty precipitation occurs during the growing season. Over a
large portion of the arid and semiarid region the summers are
almost rainless and the bulk of the precipitation comes in the
winter, late fall, or early spring when plants are not growing. If
the rains that fall during the growing season are indispensable in
crop production, the possible area to be reclaimed by dry-farming
will be greatly limited. Even when much of the total precipitation
comes in summer, the amount in dry-farm districts is seldom
sufficient for the proper maturing of crops. In fact, successful
dry-farming depends chiefly upon the success with which the rains
that fall during any season of the year may be stored and kept in
the soil until needed by plants in their growth. The fundamental
operations of dry-farming include a soil treatment which enables
the largest possible proportion of the annual precipitation to be
stored in the soil. For this purpose, the deep, somewhat porous
soils, characteristic of arid regions, are unusually well adapted.
Alway's demonstration
An important and unique demonstration of the possibility of
bringing crops to maturity on the moisture stored in the soil at
the time of planting has been made by Alway. Cylinders of
galvanized iron, 6 feet long, were filled with soil as nearly as
possible in its natural position and condition Water was added
until seepage began, after which the excess was allowed to drain
away. When the seepage had closed, the cylinders were entirely
closed except at the surface. Sprouted grains of spring wheat were
placed in the moist surface soil, and 1 inch of dry soil added to
the surface to prevent evaporation. No more water was added; the
air of the greenhouse was kept as dry as possible. The wheat
developed normally. The first ear was ripe in 132 days after
planting and the last in 143 days. The three cylinders of soil
from semiarid western Nebraska produced 37.8 grams of straw and 29
ears, containing 415 kernels weighing 11.188 grams. The three
cylinders of soil from humid eastern Nebraska produced only 11.2
grams of straw and 13 ears containing 114 kernels, weighing 3
grams. This experiment shows conclusively that rains are not
needed during the growing season, if the soil is well filled with
moisture at seedtime, to bring crops to maturity.
What becomes of the rainfall ?
The water that falls on the land is disposed of in three ways:
First, under ordinary conditions, a large portion runs off without
entering the soil; secondly, a portion enters the soil, but
remains near the surface, and is rapidly evaporated back into the
air; and, thirdly, a portion enters the lower soil layers, from
which it is removed at later periods by several distinct
processes. The run-off is usually large and is a serious loss,
especially in dry-farming regions, where the absence of luxuriant
vegetation, the somewhat hard, sun-baked soils, and the numerous
drainage channels, formed by successive torrents, combine to
furnish the rains with an easy escape into the torrential rivers.
Persons familiar with arid conditions know how quickly the narrow
box cañons, which often drain thousands of square miles, are
filled with roaring water after a comparatively light rainfall.
The run-off
The proper cultivation of the soil diminishes very greatly the
loss due to run-off, but even on such soils the proportion may
often be very great. Farrel observed at one of the Utah stations
that during a torrential rain--2.6 inches in 4 hours--the surface
of the summer fallowed plats was packed so solid that only one
fourth inch, or less than one tenth of the whole amount, soaked
into the soil, while on a neighboring stubble field, which offered
greater hindrance to the run-off, 1-1/2 inches or about 60 per
cent were absorbed.
It is not possible under any condition to prevent the run-off
altogether, although it can usually be reduced exceedingly. It is
a common dry-farm custom to plow along the slopes of the farm
instead of plowing up and down them. When this is done, the water
which runs down the slopes is caught by the succession of furrows
and in that way the runoff is diminished. During the fallow season
the disk and smoothing harrows are run along the hillsides for the
same purpose and with results that are nearly always advantageous
to the dry-farmer. Of necessity, each man must study his own farm
in order to devise methods that will prevent the run-off.
The structure of soils
Before examining more closely the possibility of storing water in
soils a brief review of the structure of soils is desirable. As
previously explained, soil is essentially a mixture of
disintegrated rock and the decomposing remains of plants. The rock
particles which constitute the major portion of soils vary greatly
in size. The largest ones are often 500 times the sizes of the
smallest. It would take 50 of the coarsest sand particles, and
25,000 of the finest silt particles, to form one lineal inch. The
clay particles are often smaller and of such a nature that they
cannot be accurately measured. The total number of soil particles
in even a small quantity of cultivated soil is far beyond the
ordinary limits of thought, ranging from 125,000 particles of
coarse sand to 15,625,000,000,000 particles of the finest silt in
one cubic inch. In other words, if all the particles in one cubic
inch of soil consisting of fine silt were placed side by side,
they would form a continuous chain over a thousand miles long. The
farmer, when he tills the soil, deals with countless numbers of
individual soil grains, far surpassing the understanding of the
human mind. It is the immense number of constituent soil particles
that gives to the soil many of its most valuable properties.
It must be remembered that no natural soil is made up of particles
all of which are of the same size; all sizes, from the coarsest
sand to the finest clay, are usually present. These particles of
all sizes are not arranged in the soil in a regular, orderly way;
they are not placed side by side with geometrical regularity; they
are rather jumbled together in every possible way. The larger sand
grains touch and form comparatively large interstitial spaces into
which the finer silt and clay grains filter. Then, again, the clay
particles, which have cementing properties, bind, as it were, one
particle to another. A sand grain may have attached to it
hundreds, or it may be thousands, of the smaller silt grains; or a
regiment of smaller soil grains may themselves be clustered into
one large grain by cementing power of the clay. Further, in the
presence of lime and similar substances, these complex soil grains
are grouped into yet larger and more complex groups. The
beneficial effect of lime is usually due to this power of grouping
untold numbers of soil particles into larger groups. When by
correct soil culture the individual soil grains are thus grouped
into large clusters, the soil is said to be in good tilth.
Anything that tends to destroy these complex soil grains, as, for
instance, plowing the soil when it is too wet, weakens the
crop-producing power of the soil. This complexity of structure is
one of the chief reasons for the difficulty of understanding
clearly the physical laws governing soils.
Pore-space of soils
It follows from this description of soil structure that the soil
grains do not fill the whole of the soil space. The tendency is
rather to form clusters of soil grains which, though touching at
many points, leave comparatively large empty spaces. This pore
space in soils varies greatly, but with a maximum of about 55 per
cent. In soils formed under arid conditions the percentage of
pore-space is somewhere in the neighborhood of 50 per cent. There
are some arid soils, notably gypsum soils, the particles of which
are so uniform size that the pore-space is exceedingly small. Such
soils are always difficult to prepare for agricultural purposes.
It is the pore-space in soils that permits the storage of soil-
moisture; and it is always important for the farmer so to maintain
his soil that the pore-space is large enough to give him the best
results, not only for the storage of moisture, but for the growth
and development of roots, and for the entrance into the soil of
air, germ life, and other forces that aid in making the soil fit
for the habitation of plants. This can always be best
accomplished, as will be shown hereafter, by deep plowing, when
the soil is not too wet, the exposure of the plowed soil to the
elements, the frequent cultivation of the soil through the growing
season, and the admixture of organic matter. The natural soil
structure at depths not reached by the plow evidently cannot be
vitally changed by the farmer.
Hygroscopic soil-water
Under normal conditions, a certain amount of water is always found
in all things occurring naturally, soils included. Clinging to
every tree, stone, or animal tissue is a small quantity of
moisture varying with the temperature, the amount of water in the
air, and with other well-known factors. It is impossible to rid
any natural substance wholly of water without heating it to a high
temperature. This water which, apparently, belongs to all natural
objects is commonly called hygroscopic water. Hilgard states that
the soils of the arid regions contain, under a temperature of 15°
C. and an atmosphere saturated with water, approximately 5-1/2 per
cent of hygroscopic water. In fact, however, the air over the arid
region is far from being saturated with water and the temperature
is even higher than 15° C., and the hygroscopic moisture actually
found in the soils of the dry-farm territory is considerably
smaller than the average above given. Under the conditions
prevailing in the Great Basin the hygroscopic water of soils
varies from .75 per cent to 3-1/2 per cent; the average amount is
not far from 12 per cent.
Whether or not the hygroscopic water of soils is of value in plant
growth is a disputed question. Hilgard believes that the
hygroscopic moisture can be of considerable help in carrying
plants through rainless summers, and further, that its presence
prevents the heating of the soil particles to a point dangerous to
plant roots. Other authorities maintain earnestly that the
hygroscopic soil-water is practically useless to plants.
Considering the fact that wilting occurs long before the
hygroscopic water contained in the soil is reached, it is very
unlikely that water so held is of any real benefit to plant
growth.
Gravitational water
It often happens that a portion of the water in the soil is under
the immediate influence of gravitation. For instance, a stone
which, normally, is covered with hygroscopic water is dipped into
water The hydroscopic water is not thereby affected, but as the
stone is drawn out of the water a good part of the water runs off.
This is gravitational water That is, the gravitational water of
soils is that portion of the soil-water which filling the soil
pores, flows downward through the soil under the influence of
gravity. When the soil pores are completely filled, the maximum
amount of gravitational water is found there. In ordinary dry-farm
soils this total water capacity is between 35 and 40 per cent of
the dry weight of soil.
The gravitational soil-water cannot long remain in that condition;
for, necessarily, the pull of gravity moves it downward through
the soil pores and if conditions are favorable, it finally reaches
the standing water-table, whence it is carried to the great
rivers, and finally to the ocean. In humid soils, under a large
precipitation, gravitational water moves down to the standing
water-table after every rain. In dry-farm soils the gravitational
water seldom reaches the standing water-table; for, as it moves
downward, it wets the soil grains and remains in the capillary
condition as a thin film around the soil grains.
To the dry-farmer, the full water capacity is of importance only
as it pertains to the upper foot of soil. If, by proper plowing
and cultivation, the upper soil be loose and porous, the
precipitation is allowed to soak quickly into the soil, away from
the action of the wind and sun. From this temporary reservoir, the
water, in obedience to the pull of gravity, will move slowly
downward to the greater soil depths, where it will be stored
permanently until needed by plants. It is for this reason that
dry-farmers find it profitable to plow in the fall, as soon as
possible after harvesting. In fact, Campbell advocates that the
harvester be followed immediately by the disk, later to be
followed by the plow The essential thing is to keep the topsoil
open and receptive to a rain.
Capillary soil-water
The so-called capillary soil-water is of greatest importance to
the dry-farmer. This is the water that clings as a film around a
marble that has been dipped into water. There is a natural
attraction between water and nearly all known substances, as is
witnessed by the fact that nearly all things may be moistened. The
water is held around the marble because the attraction between the
marble and the water is greater than the pull of gravity upon the
water. The greater the attraction, the thicker the film; the
smaller the attraction, the thinner the film will be. The water
that rises in a capillary glass tube when placed in water does so
by virtue of the attraction between water and glass. Frequently,
the force that makes capillary water possible is called surface
tension.
Whenever there is a sufficient amount of water available, a thin
film of water is found around every soil grain; and where the soil
grains touch, or where they are very near together, water is held
pretty much as in capillary tubes. Not only are the soil particles
enveloped by such a film, but the plant roots foraging in the soil
are likewise covered; that is, the whole system of soil grains and
roots is covered, under favorable conditions, with a thin film of
capillary water. It is the water in this form upon which plants
draw during their periods of growth. The hygroscopic water and the
gravitational water are of comparatively little value in plant
growth.
Field capacity of soils for
capillary water
The tremendously large number of soil grains found in even a small
amount of soil makes it possible for the soil to hold very large
quantities of capillary water. To illustrate: In one cubic inch of
sand soil the total surface exposed by the soil grains varies from
42 square inches to 27 square feet; in one cubic inch of silt
soil, from 27 square feet to 72 square feet, and in one cubic inch
of an ordinary soil the total surface exposed by the soil grains
is about 25 square feet. This means that the total surface of the
soil grains contained in a column of soil 1 square foot at the top
and 10 feet deep is approximately 10 acres. When even a thin film
of water is spread over such a large area, it is clear that the
total amount of water involved must be large It is to be noticed,
therefore, that the fineness of the soil particles previously
discussed has a direct bearing upon the amount of water that soils
may retain for the use of plant growth. As the fineness of the
soil grains increases, the total surface increases' and the
water-holding capacity also increases.
Naturally, the thickness of a water film held around the soil
grains is very minute. King has calculated that a film 275
millionths of an inch thick, clinging around the soil particles,
is equivalent to 14.24 per cent of water in a heavy clay; 7.2 per
cent in a loam; 5.21 per cent in a sandy loam, and 1.41 per cent
in a sandy soil.
It is important to know the largest amount of water that soils can
hold in a capillary condition, for upon it depend, in a measure,
the possibilities of crop production under dry-farming conditions.
King states that the largest amount of capillary water that can be
held in sandy loams varies from 17.65 per cent to 10.67 per cent;
in clay loams from 22.67 per cent to 18.16 per cent, and in humus
soils (which are practically unknown in dry-farm sections) from
44.72 per cent to 21.29 per cent. These results were not obtained
under dry-farm conditions and must be confirmed by investigations
of arid soils.
The water that falls upon dry-farms is very seldom sufficient in
quantity to reach the standing water-table, and it is necessary,
therefore, to determine the largest percentage of water that a
soil can hold under the influence of gravity down to a depth of 8
or 10 feet--the depth to which the roots penetrate and in which
root action is distinctly felt. This is somewhat difficult to
determine because the many conflicting factors acting upon the
soil-water are seldom in equilibrium. Moreover, a considerable
time must usually elapse before the rain-water is thoroughly
distributed throughout the soil. For instance, in sandy soils, the
downward descent of water is very rapid; in clay soils, where the
preponderance of fine particles makes minute soil pores, there is
considerable hindrance to the descent of water, and it may take
weeks or months for equilibrium to be established. It is believed
that in a dry-farm district, where the major part of the
precipitation comes during winter, the early springtime, before
the spring rains come, is the best time for determining the
maximum water capacity of a soil. At that season the
water-dissipating influences, such as sunshine and high
temperature, are at a minimum, and a sufficient time has elapsed
to permit the rains of fall and winter to distribute themselves
uniformly throughout the soil. In districts of high summer
precipitation, the late fall after a fallow season will probably
be the best time for the determination of the field-water
capacity.
Experiments on this subject have been conducted at the Utah
Station. As a result of several thousand trials it was found that,
in the spring, a uniform, sandy loam soil of true arid properties
contained, from year to year, an average of nearly 16-1/2 per cent
of water to a depth of 8 feet. This appeared to be practically the
maximum water capacity of that soil under field conditions, and it
may be called the field capacity of that soil for capillary water.
Other experiments on dry-farms showed the field capacity of a clay
soil to a depth of 8 feet to be 19 per cent; of a clay loam, to be
18 per cent; of a loam, 17 per cent; of another loam somewhat more
sandy, 16 per cent; of a sandy loam, 14-1/2 per cent; and of a
very sandy loam, 14 per cent. Leather found that in the calcareous
arid soil of India the upper 5 feet contained 18 per cent of water
at the close of the wet season.
It may be concluded, therefore, that the field-water capacities of
ordinary dry-farm soils are not very high, ranging from 15 to 20
per cent, with an average for ordinary dry-farm soils in the
neighborhood of 16 or 17 per cent. Expressed in another way this
means that a layer of water from 2 to 3 inches deep can be stored
in the soil to a depth of 12 inches. Sandy soils will hold less
water than clayey ones. It must not be forgotten that in the
dry-farm region are numerous types of soils, among them some
consisting chiefly of very fine soil grains and which would;
consequently, possess field-water capacities above the average
here stated. The first endeavor of the dry-farmer should be to
have the soil filled to its full field-water capacity before a
crop is planted.
Downward movement of
soil-moisture
One of the chief considerations in a discussion of the storing of
water in soils is the depth to which water may move under ordinary
dry-farm conditions. In humid regions, where the water table is
near the surface and where the rainfall is very abundant, no
question has been raised concerning the possibility of the descent
of water through the soil to the standing water. Considerable
objection, however, has been offered to the doctrine that the
rainfall of arid districts penetrates the soil to any great
extent. Numerous writers on the subject intimate that the rainfall
under dry-farm conditions reaches at the best the upper 3 or 4
feet of soil. This cannot be true, for the deep rich soils of the
arid region, which never have been disturbed by the husbandman,
are moist to very great depths. In the deserts of the Great Basin,
where vegetation is very scanty, soil borings made almost anywhere
will reveal the fact that moisture exists in considerable
quantities to the full depth of the ordinary soil auger, usually
10 feet. The same is true for practically every district of the
arid region.
Such water has not come from below, for in the majority of cases
the standing water is 50 to 500 feet below the surface. Whitney
made this observation many years ago and reported it as a striking
feature of agriculture in arid regions, worthy of serious
consideration. Investigations made at the Utah Station have shown
that undisturbed soils within the Great Basin frequently contain,
to a depth of 10 feet, an amount of water equivalent to 2 or 3
years of the rainfall which normally occurs in that locality.
These quantities of water could not be found in such soils,
unless, under arid conditions, water has the power to move
downward to considerably greater depths than is usually believed
by dry-farmers.
In a series of irrigation experiments conducted at the Utah
Station it was demonstrated that on a loam soil, within a few
hours after an irrigation, some of the water applied had reached
the eighth foot, or at least had increased the percentage of water
in the eighth foot. In soil that was already well filled with
water, the addition of water was felt distinctly to the full depth
of 8 feet. Moreover, it was observed in these experiments that
even very small rains caused moisture changes to considerable
depths a few hours after the rain was over. For instance, 0.14 of
an inch of rainfall was felt to a depth of 2 feet within 3 hours;
0.93 of an inch was felt to a depth of 3 feet within the same
period.
To determine whether or not the natural winter precipitation, upon
which the crops of a large portion of the dry-farm territory
depend, penetrates the soil to any great depth a series of tests
were undertaken. At the close of the harvest in August or
September the soil was carefully sampled to a depth of 8 feet, and
in the following spring similar samples were taken on the same
soils to the same depth. In every case, it was found that the
winter precipitation had caused moisture changes to the full depth
reached by the soil auger. Moreover, these changes were so great
as to lead the investigators to believe that moisture changes had
occurred to greater depths.
In districts where the major part of the precipitation occurs
during the summer the same law is undoubtedly in operation; but,
since evaporation is most active in the summer, it is probable
that a smaller proportion reaches the greater soil depths. In the
Great Plains district, therefore, greater care will have to be
exercised during the summer in securing proper water storage than
in the Great Basin, for instance. The principle is, nevertheless,
the same. Burr, working under Great Plains conditions in Nebraska,
has shown that the spring and summer rains penetrate the soil to
the depth of 6 feet, the average depth of the borings, and that it
undoubtedly affects the soil-moisture to the depth of 10 feet. In
general, the dry-farmer may safely accept the doctrine that the
water that falls upon his land penetrates the soil far beyond the
immediate reach of the sun, though not so far away that plant
roots cannot make use of it.
Importance of a moist subsoil
In the consideration of the downward movement of soil-water it is
to be noted that it is only when the soil is tolerably moist that
the natural precipitation moves rapidly and freely to the deeper
soil layers. When the soil is dry, the downward movement of the
water is much slower and the bulk of the water is then stored near
the surface where the loss of moisture goes on most rapidly. It
has been observed repeatedly in the investigations at the Utah
Station that when desert land is broken for dry-farm purposes and
then properly cultivated, the precipitation penetrates farther and
farther into the soil with every year of cultivation. For example,
on a dry-farm, the soil of which is clay loam, and which was
plowed in the fall of 1904 and farmed annually thereafter, the
eighth foot contained in the spring of 1905, 6.59 per cent of
moisture; in the spring of 1906, 13.11 per cent, and in the spring
of 1907, 14.75 per cent of moisture. On another farm, with a very
sandy soil and also plowed in the fall of 1904, there was found in
the eighth foot in the spring of 1905, 5.63 per cent of moisture,
in the spring of 1906, 11.41 per cent of moisture, and in the
spring of 1907, 15.49 per cent of moisture. In both of these
typical cases it is evident that as the topsoil was loosened, the
full field water capacity of the soil was more nearly approached
to a greater depth. It would seem that, as the lower soil layers
are moistened, the water is enabled, so to speak, to slide down
more easily into the depths of the soil.
This is a very important principle for the dry farmer to
understand. It is always dangerous to permit the soil of a
dry-farm to become very dry, especially below the first foot.
Dry-farms should be so manipulated that even at the harvesting
season a comparatively large quantity of water remains in the soil
to a depth of 8 feet or more. The larger the quantity of water in
the soil in the fall, the more readily and quickly will the water
that falls on the land during the resting period of fall, winter,
and early spring sink into the soil and move away from the
topsoil. The top or first foot will always contain the largest
percentage of water because it is the chief receptacle of the
water that falls as rain or snow but when the subsoil is properly
moist, the water will more completely leave the topsoil. Further,
crops planted on a soil saturated with water to a depth of 8 feet
are almost certain to mature and yield well.
If the field-water capacity has not been filled, there is always
the danger that an unusually dry season or a series of hot winds
or other like circumstances may either seriously injure the crop
or cause a complete failure. The dry-farmer should keep a surplus
of moisture in the soil to be carried over from year to year, just
as the wise business man maintains a sufficient working capital
for the needs of his business. In fact, it is often safe to advise
the prospective dry-farmer to plow his newly cleared or broken
land carefully and then to grow no crop on it the first year, so
that, when crop production begins, the soil will have stored in it
an amount of water sufficient to carry a crop over periods of
drouth. Especially in districts of very low rainfall is this
practice to be recommended. In the Great Plains area, where the
summer rains tempt the farmer to give less attention to the
soil-moisture problem than in the dry districts with winter
precipitation farther West, it is important that a fallow season
be occasionally given the land to prevent the store of soil
moisture from becoming dangerously low.
To what extent is the rainfall
stored in soils?
What proportion of the actual amount of water falling upon the
soil can be stored in the soil and carried over from season to
season? This question naturally arises in view of the conclusion
that water penetrates the soil to considerable depths. There is
comparatively little available information with which to answer
this question, because the great majority of students of soil
moisture have concerned themselves wholly with the upper two,
three, or four feet of soil. The results of such investigations
are practically useless in answering this question. In humid
regions it may be very satisfactory to confine soil-moisture
investigations to the upper few feet; but in arid regions, where
dry-farming is a living question, such a method leads to erroneous
or incomplete conclusions.
Since the average field capacity of soils for water is about 2.5
inches per foot, it follows that it is possible to store 25 inches
of water in 10 feet of soil. This is from two to one and a half
times one year's rainfall over the better dry-farming sections.
Theoretically, therefore, there is no reason why the rainfall of
one season or more could not be stored in the soil. Careful
investigations have borne out this theory. Atkinson found, for
example, at the Montana Station, that soil, which to a depth of 9
feet contained 7.7 per cent of moisture in the fall contained 11.5
per cent in the spring and, after carrying it through the summer
by proper methods of cultivation, 11 per cent.
It may certainly be concluded from this experiment that it is
possible to carry over the soil moisture from season to season.
The elaborate investigations at the Utah Station have demonstrated
that the winter precipitation, that is, the precipitation that
comes during the wettest period of the year, may be retained in a
large measure in the soil. Naturally, the amount of the natural
precipitation accounted for in the upper eight feet will depend
upon the dryness of the soil at the time the investigation
commenced. If at the beginning of the wet season the upper eight
feet of soil are fairly well stored with moisture, the
precipitation will move down to even greater depths, beyond the
reach of the soil auger. If, on the other hand, the soil is
comparatively dry at the beginning of the season, the natural
precipitation will distribute itself through the upper few feet,
and thus be readily measured by the soil auger.
In the Utah investigations it was found that of the water which
fell as rain and snow during the winter, as high as 95-1/2 per
cent was found stored in the first eight feet of soil at the
beginning of the growing season. Naturally, much smaller
percentages were also found, but on an average, in soils somewhat
dry at the beginning of the dry season, more than three fourths of
the natural precipitation was found stored in the soil in the
spring. The results were all obtained in a locality where the bulk
of the precipitation comes in the winter, yet similar results
would undoubtedly be obtained where the precipitation occurs
mainly in the summer. The storage of water in the soil cannot be a
whit less important on the Great Plains than in the Great Basin.
In fact, Burr has clearly demonstrated for western Nebraska that
over 50 per cent of the rainfall of the spring and summer may be
stored in the soil to the depth of six feet. Without question,
some is stored also at greater depths.
All the evidence at hand shows that a large portion of the
precipitation falling upon properly prepared soil, whether it be
summer or winter, is stored in the soil until evaporation is
allowed to withdraw it Whether or not water so stored may be made
to remain in the soil throughout the season or the year will be
discussed in the next chapter. It must be said, however, that the
possibility of storing water in the soil, that is, making the
water descend to relatively great soil depths away from the
immediate and direct action of the sunshine and winds, is the most
fundamental principle in successful dry-farming.
The fallow
It may be safely concluded that a large portion of the water that
falls as rain or snow may be stored in the soil to considerable
depths (eight feet or more). However, the question remains, Is it
possible to store the rainfall of successive years in the soil for
the use of one crop? In short, Does the practice of clean
fallowing or resting the ground with proper cultivation for one
season enable the farmer to store in the soil the larger portion
of the rainfall of two years, to be used for one crop? It is
unquestionably true, as will be shown later, that clean fallowing
or "summer tillage" is one of the oldest and safest practices of
dry-farming as practiced in the West, but it is not generally
understood why fallowing is desirable.
Considerable doubt has recently been cast upon the doctrine that
one of the beneficial effects of fallowing in dry-farming is to
store the rainfall of successive seasons in the soil for the use
of one crop. Since it has been shown that a large proportion of
the winter precipitation can be stored in the soil during the wet
season, it merely becomes a question of the possibility of
preventing the evaporation of this water during the drier season.
As will be shown in the next chapter, this can well be effected by
proper cultivation.
There is no good reason, therefore, for believing that the
precipitation of successive seasons may not be added to water
already stored in the soil. King has shown that fallowing the soil
one year carried over per square foot, in the upper four feet,
9.38 pounds of water more than was found in a cropped soil in a
parallel experiment; and, moreover, the beneficial effect of this.
water advantage was felt for a whole succeeding season. King
concludes, therefore, that one of the advantages of fallowing is
to increase the moisture content of the soil. The Utah experiments
show that the tendency of fallowing is always to increase the
soil-moisture content. In dry-farming, water is the critical
factor, and any practice that helps to conserve water should be
adopted. For that reason, fallowing, which gathers soil-moisture,
should be strongly advocated. In Chapter IX another important
value of the fallow will be discussed.
In view of the discussion in this chapter it is easily understood
why students of soil-moisture have not found a material increase
in soil-moisture due to fallowing. Usually such investigations
have been made to shallow depths which already were fairly well
filled with moisture. Water falling upon such soils would sink
beyond the depth reached by the soil augers, and it became
impossible to judge accurately of the moisture-storing advantage
of the fallow. A critical analysis of the literature on this
subject will reveal the weakness of most experiments in this
respect.
It may be mentioned here that the only fallow that should be
practiced by the dry-farmer is the clean fallow. Water storage is
manifestly impossible when crops are growing upon a soil. A
healthy crop of sagebrush, sunflowers, or other weeds consumes as
much water as a first-class stand of corn, wheat, or potatoes.
Weeds should be abhorred by the farmer. A weedy fallow is a sure
forerunner of a crop failure. How to maintain a good fallow is
discussed in Chapter VIII, under the head of Cultivation.
Moreover, the practice of fallowing should be varied with the
climatic conditions. In districts of low rainfall, 10-15 inches,
the land should be clean summer-fallowed every other year; under
very low rainfall perhaps even two out of three years; in
districts of more abundant rainfall, 15-20 inches, perhaps one
year out of every three or four is sufficient. Where the
precipitation comes during the growing season, as in the Great
Plains area, fallowing for the storage of water is less important
than where the major part of the rainfall comes during the fall
and winter. However, any system of dry-farming that omits
fallowing wholly from its practices is in danger of failure in dry
years.
Deep plowing for water storage
It has been attempted in this chapter to demonstrate that water
falling upon a soil may descend to great depths, and may be stored
in the soil from year to year, subject to the needs of the crop
that may be planted. By what cultural treatment may this downward
descent of the water be accelerated by the farmer? First and
foremost, by plowing at the right time and to the right depth.
Plowing should be done deeply and thoroughly so that the falling
water may immediately be drawn down to the full depth of the
loose, spongy, plowed soil, away from the action of the sunshine
or winds. The moisture thus caught will slowly work its way down
into the lower layers of the soil. Deep plowing is always to be
recommended for successful dry-farming.
In humid districts where there is a great difference between the
soil and the subsoil, it is often dangerous to turn up the
lifeless subsoil, but in arid districts where there is no real
differentiation between the soil and the subsoil, deep plowing may
safely be recommended. True, occasionally, soils are found in the
dry-farm territory which are underlaid near the surface by an
inert clay or infertile layer of lime or gypsum which forbids the
farmer putting the plow too deeply into the soil. Such soils,
however' are seldom worth while trying for dry-farm purposes. Deep
plowing must be practiced for the best dry-farming results.
It naturally follows that subsoiling should be a beneficial
practice on dry-farms. Whether or not the great cost of subsoiling
is offset by the resulting increased yields is an open question;
it is, in fact, quite doubtful. Deep plowing done at the right
time and frequently enough is possibly sufficient. By deep plowing
is meant stirring or turning the soil to a depth of six to ten
inches below the surface of the land.
Fall plowing far water storage
It is not alone sufficient to plow and to plow deeply; it is also
necessary that the plowing be done at the right time. In the very
great majority of cases over the whole dry-farm territory, plowing
should be done in the fall. There are three reasons for this:
First, after the crop is harvested, the soil should be stirred
immediately, so that it can be exposed to the full action of the
weathering agencies, whether the winters be open or closed. If for
any reason plowing cannot be done early it is often advantageous
to follow the harvester with a disk and to plow later when
convenient. The chemical effect on the soil resulting from the
weathering, made possible by fall plowing, as will be shown in
Chapter IX, is of itself so great as to warrant the teaching of
the general practice of fall plowing. Secondly, the early stirring
of the soil prevents evaporation of the moisture in the soil
during late summer and the fall. Thirdly, in the parts of the
dry-farm territory where much precipitation occurs in the fall,
winter, or early spring, fall plowing permits much of this
precipitation to enter the soil and be stored there until needed
by plants.
A number of experiment stations have compared plowing done in the
early fall with plowing done late in the fall or in the spring,
and with almost no exception it has been found that early fall
plowing is water-conserving and in other ways advantageous. It was
observed on a Utah dry-farm that the fall-plowed land contained,
to a depth of 10 feet, 7.47 acre-inches more water than the
adjoining spring-plowed land--a saving of nearly one half of a
year's precipitation. The ground should be plowed in the early
fall as soon as possible after the crop is harvested. It should
then be left in the rough throughout the winter, so that it may be
mellowed and broken down by the elements. The rough lend further
has a tendency to catch and hold the snow that may be blown by the
wind, thus insuring a more even distribution of the water from the
melting snow.
A common objection to fall plowing is that the ground is so dry in
the fall that it does not plow up well, and that the great dry
clods of earth do much to injure the physical condition of the
soil. It is very doubtful if such an objection is generally valid,
especially if the soil is so cropped as to leave a fair margin of
moisture in the soil at harvest time. The atmospheric agencies
will usually break down the clods, and the physical result of the
treatment will be beneficial. Undoubtedly, the fall plowing of dry
land is somewhat difficult, but the good results more than pay the
farmer for his trouble. Late fall plowing, after the fall rains
have softened the land, is preferable to spring plowing. If for
any reason the farmer feels that he must practice spring plowing,
he should do it as early as possible in the spring. Of course, it
is inadvisable to plow the soil when it is so wet as to injure its
tilth seriously, but as soon as that danger period has passed, the
plow should be placed in the ground. The moisture in the soil will
thereby be conserved, and whatever water may fall during the
spring months will be conserved also. This is of especial
importance in the Great Plains region and in any district where
the precipitation comes in the spring and winter months.
Likewise, after fall plowing, the land must be well stirred in the
early spring with the disk harrow or a similar implement, to
enable the spring rains to enter the soil easily and to prevent
the evaporation of the water already stored. Where the rainfall is
quite abundant and the plowed land has been beaten down by the
frequent rains, the land should be plowed again in the spring.
Where such conditions do not exist, the treatment of the soil with
the disk and harrow in the spring is usually sufficient.
In recent dry-farm experience it has been fairly completely
demonstrated that, providing the soil is well stored with water,
crops will mature even if no rain falls during the growing season.
Naturally, under most circumstances, any rains that may fall on a
well-prepared soil during the season of crop growth will tend to
increase the crop yield, but some profitable yield is assured, in
spite of the season, if the soil is well stored with water at seed
time. This is an important principle in the system of dry-farming.
THE demonstration in the last chapter that the water which falls
as rain or snow may be stored in the soil for the use of plants is
of first importance in dry-farming, for it makes the farmer
independent, in a large measure, of the distribution of the
rainfall. The dry-farmer who goes into the summer with a soil well
stored with water cares little whether summer rains come or not,
for he knows that his crops will mature in spite of external
drouth. In fact, as will be shown later, in many dry-farm sections
where the summer rains are light they are a positive detriment to
the farmer who by careful farming has stored his deep soil with an
abundance of water. Storing the soil with water is, however, only
the first step in making the rains of fall, winter, or the
preceding year available for plant growth. As soon as warm growing
weather comes, water-dissipating forces come into play, and water
is lost by evaporation. The farmer must, therefore, use all
precautions to keep the moisture in the soil until such time as
the roots of the crop may draw it into the plants to be used in
plant production. That is, as far as possible, direct evaporation
of water from the soil must be prevented.
Few farmers really realize the immense possible annual evaporation
in the dry-farm territory. It is always much larger than the total
annual rainfall. In fact, an arid region may be defined as one in
which under natural conditions several times more water evaporates
annually from a free water surface than falls as rain and snow.
For that reason many students of aridity pay little attention to
temperature, relative humidity, or winds, and simply measure the
evaporation from a free water surface in the locality in question.
In order to obtain a measure of the aridity, MacDougal has
constructed the following table, showing the annual precipitation
and the annual evaporation at several well-known localities in the
dry-farm territory.
True, the localities included in the following table are extreme,
but they illustrate the large possible evaporation, ranging from
about six to thirty-five times the precipitation. At the same time
it must be borne in mind that while such rates of evaporation may
occur from free water surfaces, the evaporation from agricultural
soils under like conditions is very much smaller.
| Place | Annual
Precipitation (In Inches) |
Annual
Evaporation (In Inches) |
Ratio |
| El Paso, Texas | 9.23 | 80 | 8.7 |
| Fort Wingate, New Mexico | 14.00 | 80 | 5.7 |
| Fort Yuma, Arizona | 2.84 | 100 | 35.2 |
| Tucson, AZ | 11.74 | 90 | 7.7 |
| Mohave, CA | 4.97 | 95 | 19.1 |
| Hawthorne, Nevada | 4.50 | 80 | 17.5 |
| Winnemucca, Nevada | 9.51 | 80 | 9.6 |
| St. George, Utah | 6.46 | 90 | 13.9 |
| Fort Duchesne, Utah | 6.49 | 75 | 11.6 |
| Pineville, Oregon | 9.01 | 70 | 7.8 |
| Lost River, Idaho | 8.47 | 70 | 8.3 |
| Laramie, Wyoming | 9.81 | 70 | 7.1 |
| Torres, Mexico | 16.97 | 100 | 6.0 |
| Temperature in Degrees F. | Grains of Water held in One Cubic Foot of Air |
| 32 | 2.126 |
| 40 | 2.862 |
| 50 | 4.089 |
| 60 | 5.756 |
| 70 | 7.992 |
| 80 | 10.949 |
| 90 | 14.810 |
| 100 | 19.790 |
| Per cent of water in | 1st foot | 2nd foot |
3rd foot |
4th foot |
5th foot |
6th foot |
7th foot |
8th foot |
Avg |
| Early spring | 20.84 | 20.06 | 19.62 | 18.28 | 18.70 | 14.29 | 14.48 | 13.83 | 17.51 |
| Midsummer | 8.83 | 8.87 | 11.03 | 9.59 | 11.27 | 11.03 | 8.95 | 9.47 | 9.88 |
Capillary soil-moisture moves from
particle to particle until the surface is reached. The closer the
soil grains are packed together, the greater the number of points
or contact, and the more easily will the movement of the soil-
moisture proceed. If by any means a layer of the soil is so
loosened as to reduce the number of points of contact, the
movement of the soil-moisture is correspondingly hindered. The
process is somewhat similar to the experience in large r airway
stations. Just before train time a great crowd of people is
gathered outside or the gates ready to show their tickets. If one
gate is opened, a certain number of passengers can pass through
each minute;
if two are opened, nearly twice as many may be admitted in the
same time; if more gates are opened, the passengers will be able
to enter the train more rapidly. The water in the lower layers of
the soil is ready to move upward whenever a call is made upon it.
To reach the surface it must pass from soil grain to soil grain,
and the larger the number of grains that touch, the more quickly
and easily will the water reach the surface, for the points of
contact of the soil particles may be likened to the gates of the
railway station. Now if, by a thorough stirring and loosening of
the topsoil, the number of points of contact between the top and
subsoil is greatly reduced, the upward flow of water is thereby
largely checked. Such a loosening of the topsoil for the purpose
of reducing evaporation from the topsoil has come to be called
cultivation, and includes plowing, harrowing, disking, hoeing, and
other cultural operations by which the topsoil is stirred. The
breaking of the points of contact between the top and subsoil is
undoubtedly the main reason for the efficiency of cultivation, but
it is also to be remembered that such stirring helps to dry the
top soil very thoroughly, and as has been explained a layer of dry
soil of itself is a very effective check upon surface evaporation.
That the stirring or cultivation of the topsoil really does
diminish evaporation of water from the soil has been shown by
numerous investigations. In 1868, Nessler found that during six
weeks of an ordinary German summer a stirred soil lost 510 grams
of water per square foot, while the adjoining compacted soil lost
1680 grams,--a saving due to cultivation of nearly 60 per cent.
Wagner, testing the correctness of Nessler's work, found, in 1874,
that cultivation reduced the evaporation a little more than 60 per
cent; Johnson, in 1878, confirmed the truth of the principle on
American soils, and Levi Stockbridge, working about the same time,
also on American soils, found that cultivation diminished
evaporation on a clay soil about 23 per cent, on a sandy loam 55
per cent, and on a heavy loam nearly 13 per cent. All the early
work done on this subject was done under humid conditions, and it
is only in recent years that confirmation of this important
principle has been obtained for the soils of the dry-farm region.
Fortier, working under California conditions, determined that
cultivation reduced the evaporation from the soil surface over 55
per cent. At the Utah Station similar experiments have shown that
the saving of soil-moisture by cultivation was 63 per cent for a
clay soil, 34 per cent for a coarse sand, and 13 per cent for a
clay loam. Further, practical experience has demonstrated time and
time again that in cultivation the dry-farmer has a powerful means
of preventing evaporation from agricultural soils.
Closely connected with cultivation is the practice of scattering
straw or other litter over the ground. Such artificial mulches are
very effective in reducing evaporation. Ebermayer found that by
spreading straw on the land, the evaporation was reduced 22 per
cent; Wagner found under similar conditions a saving of 38 per
cent, and these results have been confirmed by many other
investigators. On the modern dry-farms, which are large in area,
the artificial mulching of soils cannot become a very extensive
practice, yet it is well to bear the principle in mind. The
practice of harvesting dry-farm grain with the header and plowing
under the high stubble in the fall is a phase of cultivation for
water conservation that deserves special notice. The straw, thus
incorporated into the soil, decomposes quite readily in spite of
the popular notion to the contrary, and makes the soil more
porous, and, therefore, more effectively worked for the prevention
of evaporation. When this practice is continued for considerable
periods, the topsoil becomes rich in organic matter, which assists
in retarding evaporation, besides increasing the fertility of the
land. When straw cannot be fed to advantage, as is yet the case on
many of the western dry-farms, it would be better to scatter it
over the land than to burn it, as is often done. Anything that
covers the ground or loosens the topsoil prevents in a measure the
evaporation of the water stored in lower soil depths for the use
of crops.
Depth of cultivation
The all-important practice for the dry-farmer who is entering upon
the growing season is cultivation. The soil must be covered
continually with a deep layer of dry loose soil, which because of
its looseness and dryness makes evaporation difficult. A leading
question in connection with cultivation is the depth to which the
soil should be stirred for the best results. Many of the early
students of the subject found that a soil mulch only one half inch
in depth was effective in retaining a large part of the
soil-moisture which noncultivated soils would lose by evaporation.
Soils differ greatly in the rate of evaporation from their
surfaces. Some form a natural mulch when dried, which prevents
further water loss. Others form only a thin hard crust, below
which lies an active evaporating surface of wet soil. Soils which
dry out readily and crumble on top into a natural mulch should be
cultivated deeply, for a shallow cultivation does not extend
beyond the naturally formed mulch. In fact, on certain calcareous
soils, the surfaces of which dry out quickly and form a good
protection against evaporation, shallow cultivations often cause a
greater evaporation by disturbing the almost perfect natural
mulch. Clay or sand soils, which do not so well form a natural
mulch, will respond much better to shallow cultivations. In
general, however, the deeper the cultivation, the more effective
it is in reducing evaporation. Fortier, in the experiments in
California to which allusion has already been made, showed the
greater value of deep cultivation. During a period of fifteen
days, beginning immediately after an irrigation, the soil which
had not been mulched lost by evaporation nearly one fourth of the
total amount of water that had been added. A mulch 4 inches deep
saved about 72 per cent of the evaporation; a mulch 8 inches deep
saved about 88 per cent, and a mulch 10 inches deep stopped
evaporation almost wholly. It is a most serious mistake for the
dry-farmer, who attempts cultivation for soil-moisture
conservation, to fail to get the best results simply to save a few
cents per acre in added labor.
When to cultivate or till
It has already been shown that the rate of evaporation is greater
from a wet than from a dry surface. It follows, therefore, that
the critical time for preventing evaporation is when the soil is
wettest. After the soil is tolerably dry, a very large portion of
the soil-moisture has been lost, which possibly might have been
saved by earlier cultivation. The truth of this statement is well
shown by experiments conducted by the Utah Station. In one case on
a soil well filled with water, during a three weeks' period,
nearly one half of the total loss occurred the first, while only
one fifth fell on the third week. Of the amount lost during the
first week, over 60 per cent occurred during the first three days.
Cultivation should, therefore, be practiced as soon as possible
after conditions favorable for evaporation have been established.
This means, first, that in early spring, just as soon as the land
is dry enough to be worked without causing puddling, the soil
should be deeply and thoroughly stirred. Spring plowing, done as
early as possible, is an excellent practice for forming a mulch
against evaporation. Even when the land has been fall-plowed,
spring plowing is very beneficial, though on fall-plowed land the
disk harrow is usually used in early spring, and if it is set at
rather a sharp angle, and properly weighted, so that it cuts
deeply into the ground, it is practically as effective as spring
plowing. The chief danger to the dry-farmer is that he will permit
the early spring days to slip by until, when at last he begins
spring cultivation, a large portion of the stored soil-water has
been evaporated. It may be said that deep fall plowing, by
permitting the moisture to sink quickly into the lower layers of
soil, makes it possible to get upon the ground earlier in the
spring. In fact, unplowed land cannot be cultivated as early as
that which has gone through the winter in a plowed condition
If the land carries a fall-sown crop, early spring cultivation is
doubly important. As soon as the plants are well up in spring the
land should be gone over thoroughly several times if necessary,
with an iron tooth harrow, the teeth of which are set to slant
backward in order not to tear up the plants. The loose earth mulch
thus formed is very effective in conserving moisture; and the few
plants torn up are more than paid for by the increased water
supply for the remaining plants. The wise dry-fanner cultivates
his land, whether fallow or cropped, as early as possible in the
spring.
Following the first spring plowing, disking, or cultivation, must
come more cultivation. Soon after the spring plowing, the land
should be disked and. then harrowed. Every device should be used
to secure the formation of a layer of loose drying soil over the
land surface. The season's crop will depend largely upon the
effectiveness of this spring treatment.
As the season advances, three causes combine to permit the
evaporation of soil-moisture.
First, there is a natural tendency, under the somewhat moist
conditions of spring, for the soil to settle compactly and thus to
restore the numerous capillary connections with the lower soil
layers through which water escapes. Careful watch should therefore
be kept upon the soil surface, and whenever the mulch is not
loose, the disk or harrow should be run over the land.
Secondly, every rain of spring or summer tends to establish
connections with the store of moisture in the soil. In fact, late
spring and summer rains are often a disadvantage on dry-farms,
which by cultural treatment have been made to contain a large
store of moisture. It has been shown repeatedly that light rains
draw moisture very quickly from soil layers many feet below the
surface. The rainless summer is not feared by the dry-farmer whose
soils are fertile and rich in moisture. It is imperative that at
the very earliest moment after a spring or summer rain the topsoil
be well stirred to prevent evaporation. It thus happens that in
sections of frequent summer rains, as in the Great Plains area,
the farmer has to harrow his land many times in succession, but
the increased crop yields invariably justify the added expenditure
of effort.
Thirdly, on the summer-fallowed ground weeds start vigorously in
the spring and draw upon the soil-moisture, if allowed to grow,
fully as heavily as a crop of wheat or corn. The dry-farmer must
not allow a weed upon his land. Cultivation must he so continuous
as to make weeds an impossibility. The belief that the elements
added to the soil by weeds offset the loss of soil-moisture is
wholly erroneous. The growth of weeds on a fallow dry-farm is more
dangerous than the packed uncared-for topsoil. Many implements
have been devised for the easy killing of weeds, but none appear
to be better than the plow and the disk which are found on every
farm. (See Chapter XV.)
When crops are growing on the land, thorough summer cultivation is
somewhat more difficult, but must be practiced for the greatest
certainty of crop yields. Potatoes, corn, and similar crops may be
cultivated with comparative ease, by the use of ordinary
cultivators. With wheat and the other small grains, generally, the
damage done to the crop by harrowing late in the season is too
great, and reliance is therefore placed on the shading power of
the plants to prevent undue evaporation. However, until the wheat
and other grains are ten to twelve inches high, it is perfectly
safe to harrow them. The teeth should be set backward to diminish
the tearing up of the plants, and the implement weighted enough to
break the soil crust thoroughly. This practice has been fully
tried out over the larger part of the dry-farm territory and found
satisfactory.
So vitally important is a permanent soil mulch for the
conservation for plant use of the water stored in the soil that
many attempts have been made to devise means for the effective
cultivation of land on which small grains and grasses are growing.
In many places plants have been grown in rows so far apart that a
man with a hoe could pass between them. Scofield has described
this method as practiced successfully in Tunis. Campbell and
others in America have proposed that a drill hole be closed every
three feet to form a path wide enough for a horse to travel in and
to pull a large spring tooth cultivator' with teeth so spaced as
to strike between the rows of wheat. It is yet doubtful whether,
under average conditions, such careful cultivation, at least of
grain crops, is justified by the returns. Under conditions of high
aridity, or where the store of soil-moisture is low, such
treatment frequently stands between crop success and failure, and
it is not unlikely that methods will be devised which will permit
of the cheap and rapid cultivation between the rows of growing
wheat. Meanwhile, the dry-farmer must always remember that the
margin under which he works is small, and that his success depends
upon the degree to which he prevents small wastes.
WATER that has entered the soil may be lost in three ways. First,
it may escape by downward seepage, whereby it passes beyond the
reach of plant roots and often reaches the standing water. In
dry-farm districts such loss is a rare occurrence, for the natural
precipitation is not sufficiently large to connect with the
country drainage, and it may, therefore, be eliminated from
consideration. Second, soil-water may be lost by direct
evaporation from the surface soil. The conditions prevailing in
arid districts favor strongly this manner of loss of
soil-moisture. It has been shown, however, in the preceding
chapter that the farmer, by proper and persistent cultivation of
the topsoil, has it in his power to reduce this loss enough to be
almost negligible in the farmer's consideration. Third, soil-water
may be lost by evaporation from the plants themselves. While it is
not generally understood, this source of loss is, in districts
where dry-farming is properly carried on, very much larger than
that resulting either from seepage or from direct evaporation.
While plants are growing, evaporation from plants, ordinarily
called transpiration, continues. Experiments performed in various
arid districts have shown that one and a half to three times more
water evaporates from the plant than directly from well-tilled
soil. To the present very little has been learned concerning the
most effective methods of checking or controlling this continual
loss of water. Transpiration, or the evaporation of water from the
plants themselves and the means of controlling this loss, are
subjects of the deepest importance to the dry-farmer.
Absorption
To understand the methods for reducing transpiration, as proposed
in this chapter, it is necessary to review briefly the manner in
which plants take water from the soil. The roots are the organs of
water absorption. Practically no water is taken into the plants by
the stems or leaves, even under conditions of heavy rainfall. Such
small quantities as may enter the plant through the stems and
leaves are of very little value in furthering the life and growth
of the plant. The roots alone are of real consequence in water
absorption. All parts of the roots do not possess equal power of
taking up soil-water. In the process of water absorption the
younger roots are most active and effective. Even of the young
roots, however, only certain parts are actively engaged in water
absorption. At the very tips of the young growing roots are
numerous fine hairs. These root-hairs, which cluster about the
growing point of the young roots, are the organs of the plant that
absorb soil-water. They are of value only for limited periods of
time, for as they grow older, they lose their power of water
absorption. In fact, they are active only when they are in actual
process of growth. It follows, therefore, that water absorption
occurs near the tips of the growing roots, and whenever a plant
ceases to grow the water absorption ceases also. The root-hairs
are filled with a dilute solution of various substances, as yet
poorly understood, which plays an important tent part in the ab
sorption of water and plant-food from the soil.
Owing to their minuteness, the root-hairs are in most cases
immersed in the water film that surrounds the soil particles, and
the soil-water is taken directly into the roots from the
soil-water film by the process known as osmosis. The explanation
of this inward movement is complicated and need not be discussed
here. It is sufficient to say that the concentration or strength
of the solution within the root-hair is of different degree from
the soil-water solution. The water tends, therefore, to move from
the soil into the root, in order to make the solutions inside and
outside of the root of the same concentration. If it should ever
occur that the soil-water and the water within the root-hair
became the same concentration, that is to say, contained the same
substances in the same proportional amounts, there would be no
further inward movement of water. Moreover, if it should happen
that the soil-water is stronger than the water within the
root-hair, the water would tend to pass from the plant into the
soil. This is the condition that prevails in many alkali lands of
the West, and is the cause of the death of plants growing on such
lands.
It is clear that under these circumstances not only water enters
the root-hairs, but many of the substances found in solution in
the soil-water enter the plant also. Among these are the mineral
substances which are indispensable for the proper life and growth
of plants. These plant nutrients are so indispensable that if any
one of them is absent, it is absolutely impossible for the plant
to continue its life functions. The indispensable plant-foods
gathered from the soil by the root-hairs, in addition to water,
are: potassium, calcium, magnesium, iron, nitrogen, and
phosphorus,--all in their proper combinations. How the plant uses
these substances is yet poorly understood, but we are fairly
certain that each one has some particular function in the life of
the plant. For instance, nitrogen and phosphorus are probably
necessary in the formation of the protein or the flesh-forming
portions of the plant, while potash is especially valuable in the
formation of starch.
There is a constant movement of the indispensable plant nutrients
after they have entered the root-hairs, through the stems and into
the leaves. This constant movement of the plant-foods depends upon
the fact that the plant consumes in its growth considerable
quantities of these substances, and as the plant juices are
diminished in their content of particular plant-foods, more enters
from the soil solution. The necessary plant-foods do not alone
enter the plant but whatever may be in solution in the soil-water
enters the plant in variable quantities. Nevertheless, since the
plant uses only a few definite substances and leaves the
unnecessary ones in solution, there is soon a cessation of the
inward movement of the unimportant constituents of the soil
solution. This process is often spoken of as selective absorption;
that is, the plant, because of its vital activity, appears to have
the power of selecting from the soil certain substances and
rejecting others.
Movement of water through plant
The soil-water, holding in solution a great variety of plant
nutrients, passes from the root-hairs into the adjoining cells and
gradually moves from cell to cell throughout the whole plant. In
many plants this stream of water does not simply pass from cell to
cell, but moves through tubes that apparently have been formed for
the specific purpose of aiding the movement of water through the
plant. The rapidity of this current is often considerable.
Ordinarily, it varies from one foot to six feet per hour, though
observations are on record showing that the movement often reaches
the rate of eighteen feet per hour. It is evident, then, that in
an actively growing plant it does not take long for the water
which is in the soil to find its way to the uppermost parts of the
plant.
The work of leaves
Whether water passes upward from cell to cell or through
especially provided tubes, it reaches at last the leaves, where
evaporation takes place. It is necessary to consider in greater
detail what takes place in leaves in order that we may more
clearly understand the loss due to transpiration. One half or more
of every plant is made up of the element carbon. The remainder of
the plant consists of the mineral substances taken from the soil
(not more than two to 10 per cent of the dry plant) and water
which has been combined with the carbon and these mineral
substances to form the characteristic products of plant life. The
carbon which forms over half of the plant substance is gathered
from the air by the leaves and it is evident that the leaves are
very active agents of plant growth. The atmosphere consists
chiefly of the gases oxygen and nitrogen in the proportion of one
to four, but associated with them are small quantities of various
other substances. Chief among the secondary constituents of the
atmosphere is the gas carbon dioxid, which is formed when carbon
burns, that is, when carbon unites with the oxygen of the air.
Whenever coal or wood or any carbonaceous substance burns, carbon
dioxid is formed. Leaves have the power of absorbing the gas
carbon dioxid from the air and separating the carbon from the
oxygen. The oxygen is returned to the atmosphere while the carbon
is retained to be used as the fundamental substance in the
construction by the plant of oils, fats, starches, sugars,
protein, and all the other products of plant growth.
This important process known as carbon assimilation is made
possible by the aid of countless small openings which exist
chicfly on the surfaces of leaves and known as "stomata." The
stomata are delicately balanced valves, exceedingly sensitive to
external influences. They are more numerous on the lower side than
on the upper side of plants. In fact, there is often five times
more on the under side than on the upper side of a leaf. It has
been estimated that 150,000 stomata or more are often found per
square inch on the under side of the leaves of ordinary cultivated
plants. The stomata or breathing-pores are so constructed that
they may open and close very readily. In wilted leaves they are
practically closed; often they also close immediately after a
rain; but in strong sunlight they are usually wide open. It is
through the stomata that the gases of the air enter the plant
through which the discarded oxygen returns to the atmosphere.
It is also through the stomata that the water which is drawn from
the soil by the roots through the stems is evaporated into the
air. There is some evaporation of water from the stems and
branches of plants, but it is seldom more than a thirtieth or a
fortieth of the total transpiration. The evaporation of water from
the leaves through the breathing-pores is the so-called
transpiration, which is the greatest cause of the loss of
soil-water under dry-farm conditions. It is to the prevention of
this transpiration that much investigation must be given by future
students of dry-farming.
Transpiration
As water evaporates through the breathing-pores from the leaves it
necessarily follows that a demand is made upon the lower portions
of the plant for more water. The effect of the loss of water is
felt throughout the whole plant and is, undoubtedly, one of the
chief causes of the absorption of water from the soil. As
evaporation is diminished the amount of water that enters the
plants is also diminished. Yet transpiration appears to be a
process wholly necessary for plant life. The question is, simply,
to what extent it may be diminished without injuring plant growth.
Many students believe that the carbon assimilation of the plant,
which is fundamentally important in plant growth, cannot be
continued unless there is a steady stream of water passing through
the plant and then evaporating from the leaves.
Of one thing we are fairly sure: if the upward stream of water is
wholly stopped for even a few hours, the plant is likely to be so
severely injured as to be greatly handicapped in its future
growth.
Botanical authorities agree that transpiration is of value to
plant growth, first, because it helps to distribute the mineral
nutrients necessary for plant growth uniformly throughout the
plant; secondly, because it permits an active assimilation of the
carbon by the leaves; thirdly, because it is not unlikely that the
heat required to evaporate water, in large part taken from the
plant itself, prevents the plant from being overheated. This last
mentioned value of transpiration is especially important in
dry-farm districts, where, during the summer, the heat is often
intense. Fourthly, transpiration apparently influences plant
growth and development in a number of ways not yet clearly
understood.
Conditions influencing
transpiration
In general, the conditions that determine the evaporation of water
from the leaves are the same as those that favor the direct
evaporation of water from soils, although there seems to be
something in the life process of the plant, a physiological
factor, which permits or prevents the ordinary water-dissipating
factors from exercising their full powers. That the evaporation of
water from the soil or from a free water surface is not the same
as that from plant leaves may be shown in a general way from the
fact that the amount of water transpired from a given area of leaf
surface may be very much larger or very much smaller than that
evaporated from an equal surface of free water exposed to the same
conditions. It is further shown by the fact that whereas
evaporation from a free water surface goes on with little or no
interruption throughout the twenty-four hours of the day,
transpiration is virtually at a standstill at night even though
the conditions for the rapid evaporation from a free water surface
are present.
Some of the conditions influencing the transpiration may be
enumerated as follows:--
First, transpiration is influenced by the relative humidity. In
dry air, under otherwise similar conditions, plants transpire more
water than in moist air though it is to be noted that even when
the atmosphere is fully saturated, so that no water evaporates
from a free water surface, the transpiration of plants still
continues in a small degree. This is explained by the observation
that since the life process of a plant produces a certain amount
of heat, the plant is always warmer than the surrounding air and
that transpiration into an atmosphere fully charged with water
vapor is consequently made possible. The fact that transpiration
is greater under a low relative humidity is of greatest importance
to the dry-farmer who has to contend with the dry atmosphere.
Second, transpiration increases with the increase in temperature;
that is, under conditions otherwise the same, transpiration is
more rapid on a warm day than on a cold one. The temperature
increase of itself, however, is not sufficient to cause
transpiration.
Third, transpiration increases with the increase of air currents,
which is to say, that on a windy day transpiration is much more
rapid than on a quiet day.
Fourth, transpiration increases with the increase of direct
sunlight. It is an interesting observation that even with the same
relative humidity, temperature, and wind, transpiration is reduced
to a minimum during the night and increases manyfold during the
day when direct sunlight is available. This condition is again to
be noted by the dry-farmer, for the dry-farm districts are
characterized by an abundance of sunshine.
Fifth, transpiration is decreased by the presence in the soil-
water of large quantities of the substances which the plant needs
for its food material. This will be discussed more fully in the
next section.
Sixth, any mechanical vibration of the plant seems to have some
effect upon the transpiration. At times it is increased and at
times it is decreased by such mechanical disturbance.
Seventh, transpiration varies also with the age of the plant. In
the young plant it is comparatively small. Just before blooming it
is very much larger and in time of bloom it is the largest in the
history of the plant. As the plant grows older transpiration
diminishes, and finally at the ripening stage it almost ceases.
Eighth, transpiration varies greatly with the crop. Not all plants
take water from the soil at the same rate. Very little is as yet
known about the relative water requirements of crops on the basis
of transpiration. As an illustration, MacDougall has reported that
sagebrush uses about one fourth as much water as a tomato plant.
Even greater differences exist between other plants. This is one
of the interesting subjects yet to be investigated by those who
are engaged in the reclamation of dry-farm districts. Moreover,
the same crop grown under different conditions varies in its rate
of transpiration. For instance, plants grown for some time under
arid conditions greatly modify their rate of transpiration, as
shown by Spalding, who reports that a plant reared under humid
conditions gave off 3.7 times as much water as the same plant
reared under arid conditions. This very interesting observation
tends to confirm the view commonly held that plants grown under
arid conditions will gradually adapt themselves to the prevailing
conditions, and in spite of the greater water dissipating
conditions will live with the expenditure of less water than would
be the case under humid conditions. Further, Sorauer found, many
years ago, that different varieties of the same crop possess very
different rates of transpiration. This also is an interesting
subject that should be more fully investigated in the future.
Ninth, the vigor of growth of a crop appears to have a strong
influence on transpiration. It does not follow, however, that the
more vigorously a crop grows, the more rapidly does it transpire
water, for it is well known that the most luxuriant plant growth
occurs in the tropics, where the transpiration is exceedingly low.
It seems to be true that under the same conditions, plants that
grow most vigorously tend to use proportionately the smallest
amount of water.
Tenth, the root system--its depth and manner of growth--influences
the rate of transpiration. The more vigorous and extensive the
root system, the more rapidly can water be secured from the soil
by the plant.
The conditions above enumerated as influencing transpiration are
nearly all of a physical character, and it must not be forgotten
that they may all be annulled or changed by a physiological
regulation. It must be admitted that the subject of transpiration
is yet poorly understood, though it is one of the most important
subjects in its applications to plant production in localities
where water is scaree. It should also be noted that nearly all of
the above conditions influencing transpiration are beyond the
control of the farmer. The one that seems most readily controlled
in ordinary agricultural practice will be discussed in the
following section.
Plant-food and transpiration
It has been observed repeatedly by students of transpiration that
the amount of water which actually evaporates from the leaves is
varied materially by the substances held in solution by the
soil-water. That is, transpiration depends upon the nature and
concentration of soil solution. This fact, though not commonly
applied even at the present time, has really been known for a very
long time. Woodward, in 1699, observed that the amount of water
transpired by a plant growing in rain water was 192.3 grams; in
spring water, 163.6 grams, and in water from the River Thames,
159.5 grams; that is, the amount of water transpired by the plant
in the comparatively pure rain water was nearly 20 per cent higher
than that used by the plant growing in the notoriously impure
water of the River Thames. Sachs, in 1859, carried on an elaborate
series of experiments on transpiration in which he showed that the
addition of potassium nitrate, ammonium sulphate or common salt to
the solution in which plants grew reduced the transpiration; in
fact, the reduction was large, varying from 10 to 75 per cent.
This was confirmed by a number of later workers, among them, for
instance, Buergerstein, who, in 1875, showed that whenever acids
were added to a soil or to water in which plants are growing, the
transpiration is increased greatly; but when alkalies of any kind
are added, transpiration decreases. This is of special interest in
the development of dry-farming, since dry-farm soils, as a rule,
contain more substances that may be classed as alkalies than do
soils maintained under humid conditions. Sour soils are very
characteristic of districts where the rainfall is abundant; the
vegetation growing on such soils transpires excessively and the
crops are consequently more subject to drouth.
The investigators of almost a generation ago also determined
beyond question that whenever a complete nutrient solution is
presented to plants, that is, a solution containing all the
necessary plant-foods in the proper proportions, the transpiration
is reduced immensely. It is not necessary that the plant-foods
should be presented in a water solution in order to effect this
reduction in transpiration; if they are added to the soil on which
plants are growing, the same effect will result. The addition of
commercial fertilizers to the soil will therefore diminish
transpiration. It was further discovered nearly half a century ago
that similar plants growing on different soils evaporate different
amounts of water from their leaves; this difference, undoubtedly,
is due to the conditions in the fertility of the soils, for the
more fertile a soil is, the richer will the soil-water be in the
necessary plant-foods. The principle that transpiration or the
evaporation of water from the plants depends on the nature and
concentration of the soil solution is of far-reaching importance
in the development of a rational practice of dry-farming.
Transpiration for a pound of dry
matter
Is plant growth proportional to transpiration? Do plants that
evaporate much water grow more rapidly than those that evaporate
less? These questions arose very early in the period characterized
by an active study of transpiration. If varying the transpiration
varies the growth, there would be no special advantage in reducing
the transpiration. From an economic point of view the important
question is this: Does the plant when its rate of transpiration is
reduced still grow with the same vigor? If that be the case, then
every effort should be made by the farmer to control and to
diminish the rate of transpiration.
One of the very earliest experiments on transpiration, conducted
by Woodward in 1699, showed that it required less water to produce
a pound of dry matter if the soil solution were of the proper
concentration and contained the elements necessary for plant
growth. Little more was done to answer the above questions for
over one hundred and fifty years. Perhaps the question was not
even asked during this period, for scientific agriculture was just
coming into being in countries where the rainfall was abundant.
However, Tschaplowitz, in 1878, investigated the subject and found
that the increase in dry matter is greatest when the transpiration
is the smallest. Sorauer, in researches conducted from 1880 to
1882, determined with almost absolute certainty that less water is
required to produce a pound of dry matter when the soil is
fertilized than when it is not fertilized. Moreover, he observed
that the enriching of the soil solution by the addition of
artificial fertilizers enabled the plant to produce dry matter
with less water. He further found that if a soil is properly
tilled so as to set free plant-food and in that way to enrich the
soil solution the water-cost of dry plant substance is decreased.
Hellriegel, in 1883, confirmed this law and laid down the law that
poor plant nutrition increases the water-cost of every pound of
dry matter produced. It was about this time that the Rothamsted
Experiment Station reported that its experiments had shown that
during periods of drouth the well-tilled and well-fertilized
fields yielded good crops, while the unfertilized fields yielded
poor crops or crop failures--indicating thereby, since rainfall
was the critical factor, that the fertility of the soil is
important in determining whether or not with a small amount of
water a good crop can be produced. Pagnoul, working in 1895 with
fescue grass, arrived at the same conclusion. On a poor clay soil
it required 1109 pounds of water to produce one pound of dry
matter, while on a rich calcareous soil only 574 pounds were
required. Gardner of the United States Department of Agriculture,
Bureau of Soils, working in 1908, on the manuring of soils, came
to the conclusion that the more fertile the soil the less water is
required to produce a pound of dry matter. He incidentally called
attention to the fact that in countries of limited rainfall this
might be a very important principle to apply in crop production.
Hopkins in his study of the soils of Illinois has repeatedly
observed, in connection with certain soils, that where the land is
kept fertile, injury from drouth is not common, implying thereby
that fertile soils will produce dry matter at a lower water-cost.
The most recent experiments on this subject, conducted by the Utah
Station, confirm these conclusions. The experiments, which covered
several years, were conducted in pots filled with different soils.
On a soil, naturally fertile, 908 pounds of water were transpired
for each pound of dry matter (corn) produced; by adding to this
soil an ordinary dressing of manure' this was reduced to 613
pounds, and by adding a small amount of sodium nitrate it was
reduced to 585 pounds. If so large a reduction could be secured in
practice, it would seem to justify the use of commercial
fertilizers in years when the dry-farm year opens with little
water stored in the soil. Similar results, as will be shown below,
were obtained by the use of various cultural methods. It may
therefore, be stated as a law, that any cultural treatment which
enables the soil-water to acquire larger quantities of plant-food
also enables the plant to produce dry matter with the use of a
smaller amount of water. In dry-farming, where the limiting factor
is water, this principle must he emphasized in every cultural
operation.
Methods of controlling
transpiration
It would appear that at present the only means possessed by the
farmer for controlling transpiration and making possible maximum
crops with the minimum amount of water in a properly tilled soil
is to keep the soil as fertile as is possible. In the light of
this principle the practices already recommended for the storing
of water and for the prevention of the direct evaporation of water
from the soil are again emphasized. Deep and frequent plowing,
preferably in the fall so that the weathering of the winter may be
felt deeply and strongly, is of first importance in liberating
plant-food. Cultivation which has been recommended for the
prevention of the direct evaporation of water is of itself an
effective factor in setting free plant-food and thus in reducing
the amount of water required by plants. The experiments at the
Utah Station, already referred to, bring out very strikingly the
value of cultivation in reducing the transpiration. For instance,
in a series of experiments the following results were obtained. On
a sandy loam, not cultivated, 603 pounds of water were transpired
to produce one pound of dry matter of corn; on the same soil,
cultivated, only 252 pounds were required. On a clay loam, not
cultivated, 535 pounds of water were transpired for each pound of
dry matter, whereas on the cultivated soil only 428 pounds were
necessary. On a clay soil, not cultivated, 753 pounds of water
were transpired for each pound of dry matter; on the cultivated
soil, only 582 pounds. The farmer who faithfully cultivates the
soil throughout the summer and after every rain has therefore the
satisfaction of knowing that he is accomplishing two very
important things: he is keeping the moisture in the soil, and he
is making it possible for good crops to be grown with much less
water than would otherwise be required. Even in the case of a
peculiar soil on which ordinary cultivation did not reduce the
direct evaporation, the effect upon the transpiration was very
marked. On the soil which was not cultivated, 451 pounds of water
were required to produce one pound of dry matter (corn), while on
the cultivated soils, though the direct evaporation was no
smaller, the number of pounds of water for each pound of dry
substance was as low as 265.
One of the chief values of fallowing lies in the liberation of the
plant-food during the fallow year, which reduces the quantity of
water required the next year for the full growth of crops. The
Utah experiments to which reference has already been made show the
effect of the previous soil treatment upon the water requirements
of crops. One half of the three types of soil had been cropped for
three successive years, while the other half had been left bare.
During the fourth year both halves were planted to corn. For the
sandy loam it was found that, on the part that had been cropped
previously, 659 pounds of water were required for each pound of
dry matter produced, while on the part that had been bare only 573
pounds were required. For the clay loam 889 pounds on the cropped
part and 550 on the previously bare part were required for each
pound of dry matter. For the clay 7466 pounds on the cropped part
and 1739 pounds on the previously bare part were required for each
pound of dry matter. These results teach clearly and emphatically
that the fertile condition of the soil induced by fallowing makes
it possible to produce dry matter with a smaller amount of water
than can be done on soils that are cropped continuously. The
beneficial effects of fallowing are therefore clearly twofold: to
store the moisture of two seasons for the use of one crop; and to
set free fertility to enable the plant to grow with the least
amount of water. It is not yet fully understood what changes occur
in fallowing to give the soil the fertility which reduces the
water needs of the plant. The researches of Atkinson in Montana,
Stewart and Graves in Utah, and Jensen in South Dakota make it
seem probable that the formation of nitrates plays an important
part in the whole process. If a soil is of such a nature that
neither careful, deep plowing at the right time nor constant crust
cultivation are sufficient to set free an abundance of plant-food,
it may be necessary to apply manures or commercial fertilizers to
the soil. While the question of restoring soil fertility has not
yet come to be a leading one in dry-farming, yet in view of what
has been said in this chapter it is not impossible that the time
will come when the farmers must give primary attention to soil
fertility in addition to the storing and conservation of
soil-moisture. The fertilizing of lands with proper plant-foods,
as shown in the last sections, tends to check transpiration and
makes possible the production of dry matter at the lowest
water-cost.
The recent practice in practically all dry-farm districts, at
least in the intermountain and far West, to use the header for
harvesting bears directly upon the subject considered in this
chapter. The high stubble which remains contains much valuable
plant-food, often gathered many feet below the surface by the
plant roots. When this stubble is plowed under there is a valuable
addition of the plant-food to the upper soil. Further, as the
stubble decays, acid substances are produced that act upon the
soil grains to set free the plant-food locked up in them. The
plowing under of stubble is therefore of great value to the
dry-farmer. The plowing under of any other organic substance has
the same effect. In both cases fertility is concentrated near the
surface, which dissolves in the soil-water and enables the crop to
mature with the Ieast quantity of water.
The lesson then to be learned from this chapter is, that it is not
aufficient for the dry-farmer to store an abundance of water in
the soil and to prevent that water from evaporating directly from
the soil; but the soil must be kept in such a state of high
fertility that plants are enabled to utilize the stored moisture
in the most economical manner. Water storage, the prevention of
evaporation, and the maintenance of soil fertility go hand in hand
in the development of a successful system of farming without
irrigation.
THE soil treatment prescribed in the preceding chapters rests upon
(1) deep and thorough plowing, done preferably in the fall; (2)
thorough cultivation to form a mulch over the surface of the land,
and (3) clean summer fallowing every other year under low rainfall
or every third or fourth year under abundant rainfall.
Students of dry-farming all agree that thorough cultivation of the
topsoil prevents the evaporation of soil-moisture, but some have
questioned the value of deep and fall plowing and the occasional
clean summer fallow. It is the purpose of this chapter to state
the findings of practical men with reference to the value of
plowing and fallowing in producing large crop yields under
dry-farm conditions.
It will be shown in Chapter XVIII that the first attempts to
produce crops without irrigation under a limited rainfall were
made independently in many diverse places. California, Utah, and
the Columbia Basin, as far as can now be learned, as well as the
Great Plains area, were all independent pioneers in the art of
dry-farming. It is a most significant fact that these diverse
localities, operating under different conditions as to soil and
climate, have developed practically the same system of
dry-farming. In all these places the best dry-farmers practice
deep plowing wherever the subsoil will permit it; fall plowing
wherever the climate will permit it; the sowing of fall grain
wherever the winters will permit it, and the clean summer fallow
every other year, or every third or fourth year. H. W. Campbell,
who has been the leading exponent of dry-farming in the Great
Plains area, began his work without the clean summer fallow as a
part of his system, but has long since adopted it for that section
of the country. It is scarcely to be believed that these
practices, developed laboriously through a long succession of
years in widely separated localities, do not rest upon correct
scientific principles. In any case, the accumulated experience of
the dry-farmers in this country confirms the doctrines of soil
tillage for dry-farms laid down in the preceding chapters.
At the Dry-Farming Congresses large numbers of practical farmers
assemble for the purpose of exchanging experiences and views. The
reports of the Congress show a great difference of opinion on
minor matters and a wonderful unanimity of opinion on the more
fundamental questions. For instance, deep plowing was recommended
by all who touched upon the subject in their remarks; though one
farmer, who lived in a locality the subsoil of which was very
inert, recommended that the depth of plowing should be increased
gradually until the full depth is reached, to avoid a succession
of poor crop years while the lifeless soil was being vivified. The
states of Utah, Montana, Wyoming, South Dakota, Colorado, Kansas,
Nebraska, and the provinces of Alberta and Saskatchewan of Canada
all specifically declared through one to eight representatives
from each state in favor of deep plowing as a fundamental practice
in dry-farming. Fall plowing, wherever the climatic conditions
make it possible, was similarly advocated by all the speakers.
Farmers in certain localities had found the soil so dry in the
fall that plowing was difficult, but Campbell insisted that even
in such places it would be profitable to use power enough to break
up the land before the winter season set in. Numerous speakers
from the states of Utah, Wyoming, Montana, Nebraska, and a number
of the Great Plains states, as well as from the Chinese Empire,
declared themselves as favoring fall plowing. Scareely a
dissenting voice was raised.
In the discussion of the clean summer fallow as a vital principle
of dry-farming a slight difference of opinion was discovered.
Farmers from some of the localities insisted that the clean summer
fallow every other year was indispensable; others that one in
three years was sufficient; and others one in four years, and a
few doubtful the wisdom of it altogether. However, all the
speakers agreed that clean and thorough cultivation should be
practiced faithfully during the spring, and fall of the fallow
year. The appreciation of the fact that weeds consume precious
moisture and fertility seemed to be general among the dry-farmers
from all sections of the country. The following states, provinces,
and countries declared themselves as being definitely and
emphatically in favor of clean summer fallowing:
California, Utah, Nevada, Washington, Montana, Idaho, Colorado,
New Mexico, North Dakota, Nebraska, Alberta, Saskatchewan, Russia,
Turkey, the Transvaal, Brazil, and Australia. Each of these many
districts was represented by one to ten or more representatives.
The only state to declare somewhat vigorously against it was from
the Great Plains area, and a warning voice was heard from the
United States Department of Agriculture. The recorded practical
experience of the farmers over the whole of the dry-farm territory
of the United States leads to the conviction that fallowing must
he accepted as a practice which resulted in successful
dry-farming. Further, the experimental leaders in the dry-farm
movement, whether working under private, state, or governmental
direction, are, with very few exceptions, strongly in favor of
deep fall plowing and clean summer fallowing as parts of the
dry-farm system.
The chief reluctance to accept clean summer fallowing as a
principle of dry-farming appears chicfly among students of the
Great Plains area. Even there it is admitted by all that a wheat
crop following a fallow year is larger and better than one
following wheat. There seem, however, to be two serious reasons
for objecting to it. First, a fear that a clean summer fallow,
practiced every second, third, or fourth year, will cause a large
diminution of the organic matter in the soil, resulting finally in
complete crop failure; and second, a belief that a hoed crop, like
corn or potatoes, exerts the same beneficial effect.
It is undoubtedly true that the thorough tillage involved in
dry-farming exposes to the action of the elements the organic
matter of the soil and thereby favors rapid oxidation. For that
reason the different ways in which organic matter may be supplied
regularly to dry-farms are pointed out in Chapter XIV. It may also
be observed that the header harvesting system employed over a
large part of the dry-farm territory leaves the large header
stubble to be plowed under, and it is probable that under such
methods more organic matter is added to the soil during the year
of cropping than is lost during the year of fallowing. It may,
moreover, be observed that thorough tillage of a crop like corn or
potatoes tends to cause a loss of the organic matter of the soil
to a degree nearly as large as is the case when a fallow field is
well cultivated. The thorough stirring of the soil under an arid
or semiarid climate, which is an essential feature of dry-farming,
will always result in a decrease in organic matter. It matters
little whether the soil is fallow or in crop during the process of
cultivation, so far as the result is concerned.
A serious matter connected with fallowing in the Great Plains area
is the blowing of the loose well-tilled soil of the fallow fields,
which results from the heavy winds that blow so steadily over a
large part of the western slope of the Mississippi Valley. This is
largely avoided when crops are grown on the land, even when it is
well tilled.
The theory, recently proposed, that in the Great Plains area,
where the rains come chicfly in summer, the growing of hoed crops
may take the place of the summer fallow, is said to be based on
experimental data not yet published. Careful and conscientious
experimenters, as Chilcott and his co-laborers, indicate in their
statements that in many cases the yields of wheat, after a hoed
crop, have been larger than after a fallow year. The doctrine has,
therefore, been rather widely disseminated that fallowing has no
place in the dry-farming of the Great Plains area and should be
replaced by the growing of hoed crops. Chilcott, who is the chief
exponent of this doctrine, declares, however, that it is only with
spring-grown crops and for a succession of normal years that
fallowing may be omitted, and that fallowing must be resorted to
as a safeguard or temporary expedient to guard against total loss
of crop where extreme drouth is anticipated; that is, where the
rainfall falls below the average. He further explains that
continuous grain cropping, even with careful plowing and spring
and fall tillage, is unsuccessful; but holds that certain
rotations of crops, including grain and a hoed crop every other
year, are often more profitable than grain alternating with clean
summer fallow. He further believes that the fallow year every
third or fourth year is sufficient for Great Plains conditions.
Jardine explains that whenever fall grain is grown in the Great
Plains area, the fallow is remarkably helpful, and in fact because
of the dry winters is practically indispensable.
This latter view is confirmed by the experimental results obtained
by Atkinson and others at the Montana Experiment Stations, which
are conducted under approximately Great Plains conditions.
It should be mentioned also that in Saskatchewan, in the north end
of the Great Plains area, and which is characteristic, except for
a lower annual temperature, of the whole area, and where
dry-farming has been practiced for a quarter of a century, the
clean summer fallow has come to be an established practice.
This recent discussion of the place of fallowing in the
agriculture of the Great Plains area illustrates what has been
said so often in this volume about the adapting of principles to
local conditions. Wherever the summer rainfall is sufficient to
mature a crop, fallowing for the purpose of storing moisture in
the soil is unnecessary; the only value of the fallow year under
such conditions would be to set free fertility. In the Great
Plains area the rainfall is somewhat higher than elsewhere in the
dry-farm territory and most of it comes in summer; and the summer
precipitation is probably enough in average years to mature crops,
providing soil conditions are favorable. The main considerations,
then, are to keep the soils open for the reception of water and to
maintain the soils in a sufficiently fertile condition to produce,
as explained in Chapter IX, plants with a minimum amount of water.
This is accomplished very largely by the year of hoed crop, when
the soil is as well stirred as under a clean fallow.
The dry-farmer must never forget that the critical element in
dry-farming is water and that the annual rainfall will in the very
nature of things vary from year to year, with the result that the
dry year, or the year with a precipitation below the average, is
sure to come. In somewhat wet years the moisture stored in the
soil is of comparatively little consequence, but in a year of
drouth it will be the main dependence of the farmer. Now, whether
a crop be hoed or not, it requires water for its growth, and land
which is continuously cropped even with a variety of crops is
likely to be so largely depleted of its moisture that, when the
year of drouth comes, failure will probably result.
The precariousness of dry-farming must be done away with. The year
of drouth must be expected every year. Only as certainty of crop
yield is assured will dry-farming rise to a respected place by the
side of other branches of agriculture. To attain such certainty
and respect clean summer fallowing every second, third, or fourth
year, according to the average rainfall, is probably
indispensable; and future investigations, long enough continued,
will doubtless confirm this prediction. Undoubtedly, a rotation of
crops, including hoed crops, will find an important place in
dry-farming, but probably not to the complete exclusion of the
clean summer fallow.
Jethro Tull, two hundred years ago, discovered that thorough
tillage of the soil gave crops that in some cases could not be
produced by the addition of manure, and he came to the erroneous
conclusion that "tillage is manure." In recent days we have
learned the value of tillage in conserving moisture and in
enabling plants to reach maturity with the least amount of water,
and we may be tempted to believe that "tillage is moisture." This,
like Tull's statement, is a fallacy and must be avoided. Tillage
can take the place of moisture only to a limited degree. Water is
the essential consideration in dry-farming, else there would be no
dry-farming.
THE careful application of the principles of soil treatment
discussed in the preceding chapters will leave the soil in good
condition for sowing, either in the fall or spring. Nevertheless,
though proper dry-farming insures a first-class seed-bed, the
problem of sowing is one of the most difficult in the successful
production of crops without irrigation. This is chiefly due to the
difficulty of choosing, under somewhat rainless conditions, a time
for sowing that will insure rapid and complete germination and the
establishmcnt of a root system capable of producing good plants.
In some respects fewer definite, reliable principles can be laid
down concerning sowing than any other principle of important
application in the practice of dry-farming. The experience of the
last fifteen years has taught that the occasional failures to
which even good dry-farmers have been subjected have been caused
almost wholly by uncontrollable unfavorable conditions prevailing
at the time of sowing.
Conditions of germination
Three conditions determine germination: (1) heat, (2) oxygen, and
(3) water. Unless these three conditions are all favorable, seeds
cannot germinate properly. The first requisite for successful seed
germination is a proper degree of heat. For every kind of seed
there is a temperature below which germination does not occur;
another, above which it does not occur, and another, the best, at
which, providing the other factors are favorable, germination will
go on most rapidly. The following table, constructed by Goodale,
shows the latest, highest, and best germination temperatures for
wheat, barley, and corn. Other seeds germinate approximately
within the same ranges of temperature:--
| Lowest | Highest | Best | |
| Wheat | 41 | 108 | 84 |
| Barley | 41 | 100 | 84 |
| Corn | 49 | 115 | 91 |
| German | Utah | |
| Rye | 58 | -- |
| Wheat | 57 | 52 |
| Oats | 58 | 43 |
| Barley | 56 | 44 |
| Corn | 44 | 57 |
| Beans | 95 | 88 |
| Lucern | 78 | 67 |
| Percent water in soil | 7.5 | 10 | 12.5 | 15 | 17.5 | 20 | 22.5 | 25 |
| Wheat in sandy loam | 0.0 | 98 | 94 | 86 | 82 | 82 | 82 | 6 |
| Wheat in clay | 30 | 48 | 84 | 94 | 84 | 82 | 86 | 58 |
| Beans in sandy loam | 0 | 0 | 20 | 46 | 66 | 18 | 8 | 9 |
| Beans in clay | 0 | 0 | 6 | 20 | 22 | 32 | 30 | 36 |
| Lucern in Sandy loam | 0 | 18 | 68 | 54 | 54 | 8 | 8 | 9 |
| Lucern in clay | 8 | 8 | 54 | 48 | 50 | 32 | 15 | 14 |
THE work of the dry-farmer is only half done when the soil has
been properly prepared, by deep plowing, cultivation, fallowing,
for the planting of the crop. The choice of the crop, its proper
seeding, and its correct care and harvesting are as important as
rational soil treatment in the successful pursuit of dry-farming.
It is true that in general the kinds of crops ordinarily
cultivated in humid regions are grown also on arid lands, but
varieties especially adapted to the prevailing dry-farm conditions
must be used if any certainty of harvest is desired. Plants
possess a marvelous power of adaptation to environment, and this
power becomes stronger as successive generations of plants are
grown under the given conditions. Thus, plants which have been
grown for long periods of time in countries of abundant rainfall
and characteristic humid climate and soil yield well under such
conditions, but usually suffer and die or at best yield scantily
if planted in hot rainless countries with deep soils. Yet, such
plants, if grown year after year under arid conditions, become
accustomed to warmth and dryness and in time will yield perhaps
nearly as well or it may be better in their new surroundings. The
dry-farmer who looks for large harvests must use every care to
secure varieties of crops that through generations of breeding
have become adapted to the conditions prevailing on his farm.
Home-grown seeds, if grown properly, are therefore of the highest
value. In fact, in the districts where dry-farming has been
practiced longest the best yielding varieties are, with very few
exceptions, those that have been grown for many successive years
on the same lands. The comparative newness of the attempts to
produce profitable crops in the present dry-farming territory and
the consequent absence of home-grown seed has rendered it wise to
explore other regions of the world, with similar climatic
conditions, but long inhabited, for suitable crop varieties. The
United States Department of Agriculture has accomplished much good
work in this direction. The breeding of new varieties by
scientific methods is also important, though really valuable
results cannot be expected for many years to come. When results do
come from breeding experiments, they will probably be of the
greatest value to the dry-farmer. Meanwhile, it must be
acknowledged that at the present, our knowledge of dry-farm crops
is extremely limited. Every year will probably bring new additions
to the list and great improvements of the crops and varieties now
recommended. The progressive dry-farmer should therefore keep in
close touch with state and government workers concerning the best
varieties to use.
Moreover, while the various sections of the dry-farming territory
are alike in receiving a small amount of rainfall, they are widely
different in other conditions affecting plant growth, such as
soils, winds, average temperature, and character and severity of
the winters. Until trials have been made in all these varying
localities, it is not safe to make unqualified recommendations of
any crop or crop variety. At the present we can only say that for
dry-farm purposes we must have plants that will produce the
maximum quantity of dry matter with the minimum quantity of water;
and that their periods of growth must be the shortest possible.
However, enough work has been done to establish some general rules
for the guidance of the dry-farmer in the selection of crops.
Undoubtedly, we have as yet had only a glimpse of the vast crop
possibilities of the dry-farming territory in the United States,
as well as in other countries.
Wheat
Wheat is the leading dry-farm crop. Every prospect indicates that
it will retain its preëminence. Not only is it the most generally
used cereal, but the world is rapidly learning to depend more and
more upon the dry-farming areas of the world for wheat production.
In the arid and semiarid regions it is now a commonly accepted
doctrine that upon the expensive irrigated lands should be grown
fruits, vegetables, sugar beets, and other intensive crops, while
wheat, corn, and other grains and even much of the forage should
be grown as extensive crops upon the non-irrigated or dry-farm
lands. It is to be hoped that the time is near at hand when it
will be a rarity to see grain grown upon irrigated soil, providing
the climatic conditions permit the raising of more extensive
crops.
In view of the present and future greatness of the wheat crop on
semiarid lands, it is very important to secure the varieties that
will best meet the varying dry-farm conditions. Much has been done
to this end, but more needs to be done. Our know]edge of the best
wheats is still fragmentary. This is even more true of other
dry-farm crops. According to Jardine, the dry-farm wheats grown at
present in the United States may be classificd as follows:--
I. Hard spring wheats:
(a) Common
(b) Durum
II. Winter wheats:
(a) Hard wheats (Crimean)
(b) Semihard wheats (Intermountain)
(c) Soft wheats (Pactfic)
The common varieties of hard spring wheats are grown
principally in districts where winter wheats have not as yet been
successful; that is, in the Dakotas, northwestern Nebraska, and
other localities with long winters and periods of alternate
thawing and severe freezing. The superior value of winter wheat
has been so clearly demonstrated that attempts are being made to
develop in every locality winter wheats that can endure the
prevailing climatic conditions. Spring wheats are also grown in a
scattering way and in small quantities over the whole dry-farm
territory. The two most valuable varieties of the common hard
spring wheat are Blue Stem and Red Fife, both well-established
varieties of excellent milling qualities, grown in immense
quantities in the Northeastern corner of the dry-farm territory of
the United States and commanding the best prices on the markets of
the world. It is notable that Red Fife originated in Russia, the
country which has given us so many good dry-farm crops.
The durum wheats or macaroni wheats, as they are often called, are
also spring wheats which promise to displace all other spring
varieties because of their excellent yields under extreme dry-farm
conditions. These wheats, though known for more than a generation
through occasional shipments from Russia, Algeria, and Chile, were
introduced to the farmers of the United States only in 1900,
through the explorations and enthusiastic advocacy of Carleton of
the United States Department of Agriculture. Since that time they
have been grown in nearly all the dryfarm states and especially in
the Great Plains area. Wherever tried they have yielded well, in
some cases as much as the old established winter varieties. The
extreme hardness of these wheats made it difficult to induce the
millers operating mills fitted for grinding softer wheats to
accept them for flourmaking purposes. This prejudice has, however,
gradually vanished, and to-day the durum wheats are in great
demand, especially for blending with the softer wheats and for the
making of macaroni. Recently the popularity of the durum wheats
among the farmers has been enhanced, owing to the discovery that
they are strongly rust resistant.
The winter wheats, as has been repeatedly suggested in
preceding chapters, are most desirable for dry-farm purposes,
wherever they can be grown, and especially in localities where a
fair precipitation occurs in the winter and spring. The hard
winter wheats are represented mainly by the Crimean group, the
chief members of which are Turkey, Kharkow, and Crimean. These
wheats also originated in Russia and are said to have been brought
to the United States a generation ago by Mennonite colonists. At
present these wheats are grown chiefly in the central and southern
parts of the Great Plains area and in Canada, though they are
rapidly spreading over the intermountain country. These are good
milling wheats of high gluten content and yielding abundantly
under dry-farm conditions. It is quite clear that these wheats
will soon displace the older winter wheats formerly grown on
dry-farms. Turkey wheat promises to become the leading dry-farm
wheat. The semisoft winter wheats are grown chiefly in the
intermountain country. They are represented by a very large number
of varieties, all tending toward softness and starchiness. This
may in part be due to climatic, soil, and irrigation conditions,
but is more likely a result of inherent qualities in the varieties
used. They are rapidly being displaced by hard varieties.
The group of soft winter wheats includes numerous varieties grown
extensively in the famous wheat districts of California, Oregon,
Washington, and northern Idaho. The main varieties are Red Russian
and Palouse Blue Stem, in Washington and Idaho, Red Chaff and
Foise in Oregon, and Defiance, Little Club, Sonora, and White
Australian in California. These are all soft, white, and rather
poor in gluten. It is believed that under given climatic, soil,
and cultural conditions, all wheat varieties will approach one
type, distinctive of the conditions in question, and that the
California wheat type is a result of prevailing unchangeable
conditions. More researeh is needed, however, before definite
principles can be laid down concerning the formation of
distinctive wheat types in the various dry-farm sections. Under
any condition, a change of seed, keeping improvement always in
view, should be baneficial.
Jardine has reminded the dry-farmers of the United States that
before the production of wheat on the dry-farms can reach its full
possibilities under any acreage, sufficient quantities must be
grown of a few varieties to affect the large markets. This is
especially important in the intermountain country where no
uniformity exists, but the warning should be heeded also by the
Pacific coast and Great Plains wheat areas. As soon as the best
varieties are found they should displace the miscellaneous
collection of wheat varieties now grown. The individual farmer can
be a law unto himself no more in wheat growing than in fruit
growing, if he desires to reap the largest reward of his efforts.
Only by uniformity of kind and quality and large production will
any one locality impress itself upon the markets and create a
demand. The changes now in progress by the dry-farmers of the
United States indicate that this lesson has been taken to heart.
The principle is equally important for all countries where
dry-farming is practiced.
Other small grains
Oats is undoubtedly a coming dry-farm crop. Several
varieties have been found which yield well on lands that receive
an average annual rainfall of less than fifteen inches. Others
will no doubt be discovered or developed as special attention is
given to dry-farm oats. Oats occurs as spring and winter
varieties, but only one winter variety has as yet found place in
the list of dry-farm crops. The leading; spring varieties of oats
are the Sixty-Day, Kherson, Burt, and Swedish Select. The one
winter variety, which is grown chiefly in Utah, is the Boswell, a
black variety originally brought from England about 1901.
Barley, like the other common grains, occurs in varieties
that grow well on dry-farms. In comparison with wheat very little
seareh has been made for dry-farm barleys, and, naturally, the
list of tested varieties is very small. Like wheat and oats,
barley occurs in spring and winter varieties, but as in the case
of oats only one winter variety has as yet found its way into the
approved list of dry-farm crops. The best dry-farm spring barleys
are those belonging to the beardless and hull-less types, though
the more common varieties also yield well, especially the
six-rowed beardless barley. The winter variety is the Tennessee
Winter, which is already well distributed over the Great Plains
district.
Rye is one of the surest dry-farm crops. It yields good
crops of straw and grain, both of which are valuable stock foods.
In fact, the great power of rye to survive and grow luxuriantly
under the most trying dry-farm conditions is the chief objection
to it. Once started, it is hard to eradicate. Properly cultivated
and used either as a stock feed or as green manure, it is very
valuable. Rye occurs as both spring and winter varieties. The
winter varieties are usually most satisfactory.
Carleton has recommended emmer as a crop peculiarly
adapted to semiarid conditions. Emmer is a species of wheat to the
berries of which the chaff adheres very closely. It is highly
prized as a stock feed. In Russia and Germany it is grown in very
large quantities. It is especially adapted to arid and semiarid
conditions, but will probably thrive best where the winters are
dry and summers wet. It exists as spring and winter varieties. is
with the other small grains, the success of emmer will depend
largely upon the satisfactory development of winter varieties.
Corn
Of all crops yet tried on dry-farms, corn is perhaps the most
uniformly successful under extreme dry conditions. If the soil
treatment and planting have been right, the failures that have
been reported may invariably be traced to the use of seed which
had not been acclimated. The American Indians grow corn which is
excellent for dry-farm purposes; many of the western farmers have
likewise produced strains that use the minimum of moisture, and,
moreover, corn brought from humid sections adapts itself to arid
conditions in a very few years. Escobar reports a native corn
grown in Mexico with low stalks and small ears that well endures
desert conditions. In extremely dry years corn does not always
produce a profitable crop of seed, but the crop as a whole, for
forage purposes, seldom fails to pay expenses and leave a margin
for profit. In wetter years there is a corresponding increase of
the corn crop. The dryfarming territory does not yet realize the
value of corn as a dry-farm crop. The known facts concerning corn
make it safe to predict, however, that its dry farm acreage will
increase rapidly, and that in time it will crowd the wheat crop
for preëminence.
Sorghums
Among dry-farm crops not popularly known are the sorghums, which
promise to become excellent yielders under arid conditions. The
sorghums are supposed to have come grown the tropical sections of
the globe, but they are now scattered over the earth in all
climes. The sorghums have been known in the United States for over
half a century, but it was only when dry-farming began to develop
so tremendously that the drouth-resisting power of the sorghums
was recalled. According to Ball, the sorghums fall into the
following classes:--
THE SORGHUMS
1. Broom corns
2. Sorgas or sweet sorghums
3. Kafirs
4. Durras
The broom corns are grown only for their brush, and are not
considered in dry-farming; the sorgas for forage and sirups, and
are especially adapted for irrigation or humid conditions, though
they are said to endure dry-farm conditions better than corn. The
Kafirs are dry-farm crops and are grown for grain and forage. This
group includes Red Kafir, White Kafir, Black-hulled White Kafir,
and White Milo, all of which are valuable for dry-farming. The
Durras are grown almost exclusively for seed and include Jerusalem
corn, Brown Durra, and Milo. The work of Ball has made Milo one of
the most important dry-farm crops. As improved, the crop is from
four to four and a half feet high, with mostly erect heads,
carrying a large quantity of seeds. Milo is already a staple crop
in parts of Texas, Oklahoma, Kansas, and New Mexico. It has
further been shown to be adapted to conditions in the Dakotas,
Nebraska, Colorado, Arizona, Utah, and Idaho. It will probably be
found, in some varietal form, valuable over the whole dry-farm
territory where the altitude is not too high and the average
temperature not too low.
It has yielded an average of forty bushels of seed to the acre.
Lucern or alfalfa
Next to human intelligence and industry, alfalfa has probably been
the chief factor in the development of the irrigated West. It has
made possible a rational system of agriculture, with the
live-stock industry and the maintenance of soil fertility as the
central considerations. Alfalfa is now being recognized as a
desirable crop in humid as well as in irrigated sections, and it
is probable that alfalfa will soon become the chief hay crop of
the United States. Originally, lucern came from the hot dry
countries of Asia, where it supplied feed to the animals of the
first historical peoples. Moreover, its long; tap roots,
penetrating sometimes forty or fifty feet into the ground, suggest
that lucern may make ready use of deeply stored soil-moisture. On
these considerations, alone, lucern should prove itself a crop
well suited for dry-farming. In fact, it has been demonstrated
that where conditions are favorable, lucern may be made to yield
profitable crops under a rainfall between twelve and fifteen
inches. Alfalfa prefers calcareous loamy soils; sandy and heavy
clay soils are not so well adapted for successful alfalfa
production. Under dry-farm conditions the utmost care must be used
to prevent too thick seeding. The vast majority of alfalfa
failures on dry-farms have resulted from an insufficient supply of
moisture for the thickly planted crop. The alfalfa field does not
attain its maturity until after the second year, and a crop which
looks just right the second year will probably be much too thick
the third and fourth years. From four to six pounds of seed per
acre are usually ample. Another main cause of failure is the
common idea that the lucern field needs little or no cultivation,
when, in fact, the alfalfa field should receive as careful soil
treatment as the wheat field. Heavy, thorough disking in spring or
fall, or both, is advisable, for it leaves the topsoil in a
condition to prevent evaporation and admit air. In Asiatic and
North African countries, lucern is frequently cultivated between
rows throughout the hot season. This has been tried by Brand in
this country and with very good results. Since the crop should
always be sown with a drill, it is comparatively easy to regulate
the distance between the rows so that cultivating implements may
be used. If thin seeding and thorough soil stirring are practiced,
lucern usually grows well, and with such treatment should become
one of the great dry-farm crops. The yield of hay is not large,
but sufficient to leave a comfortable margin of profit. Many
farmers find it more profitable to grow dry-farm lucern for seed.
In good years from fifty to one hundred and fifty dollars may be
taken from an acre of lucern seed. However, at the present, the
principles of lucern seed production are not well established, and
the seed crop is uncertain.
Alfalfa is a leguminous crop and gathers nitrogen from the air. It
is therefore a good fertilizer. The question of soil fertility
will become more important with the passing of the years, and the
value of lucern as a land improver will then be more evident than
it is to-day.
Other leguminous crops
The group of leguminous or pod-bearing crops is of great
importance; first, because it is rich in nitrogenous substances
which are valuable animal foods, and, secondly, because it has the
power of gathering nitrogen from the air, which can be used for
maintaining the fertility of the soil. Dry-farming will not be a
wholly safe practice of agriculture until suitable leguminous
crops are found and made part of the crop system. It is notable
that over the whole of the dry-farm territory of this and other
countries wild leguminous plants flourish. That is, nitrogen-
gathering plants are at work on the deserts. The farmer upsets
this natural order of things by cropping the land with wheat and
wheat only, so long as the land will produce profitably. The
leguminous plants native to dry-farm areas have not as yet been
subjected to extensive economic study, and in truth very little is
known concerning leguminous plants adapted to dry-farming.
In California, Colorado, and other dry-farm states the field pea
has been grown with great profit. Indeed it has been found much
more profitable than wheat production. The field bean, likewise,
has been grown successfully under dry-farm conditions, under a
great variety of climates. In Mexico and other southern climates,
the native population produce large quantities of beans upon their
dry lands.
Shaw suggests that sanfoin, long famous for its service to
European agriculture, may be found to be a profitable dry-farm
crop, and that sand vetch promises to become an excellent dry-farm
crop. It is very likely, however, that many of the leguminous
crops which have been developed under conditions of abundant
rainfall will be valueless on dry-farm lands. Every year will
furnish new and more complete information on this subject.
Leguminous plants will surely become important members of the
association of dry-farm crops.
Trees and shrubs
So far, trees cannot be said to be dry-farm crops, though facts
are on record that indicate that by the application of correct
dry-farm principles trees may be made to grow and yield profitably
on dry-farm lands. Of course, it is a well-known fact that native
trees of various kinds are occasionally found growing on the
deserts, where the rainfall is very light and the soil has been
given no care. Examples of such vegetation are the native cedars
found throughout the Great Basin region and the mesquite tree in
Arizona and the Southwest. Few farmers in the arid region have as
yet undertaken tree culture without the aid of irrigation.
At least one peach orchard is known in Utah which grows under a
rainfall of about fifteen inches without irrigation and produces
regularly a small crop of most delicious fruit. Parsons describes
his Colorado dry-farm orchard in which, under a rainfall of almost
fourteen inches, he grows, with great profit, cherries, plums, and
apples. A number of prospering young orchards are growing without
irrigation in the Great Plains area. Mason discovered a few years
ago two olive orchards in Arizona and the Colorado desert which,
planted about fourteen years previously, were thriving under an
annual rainfall of eight and a half and four and a half inches,
respectively. These olive orchards had been set out under canals
which later failed. Such attested facts lead to the thought that
trees may yet take their place as dry-farm crops. This hope is
strengthened when it is recalled that the great nations of
antiquity, living in countries of low rainfall, grew profitably
and without irrigation many valuable trees, some of which are
still cultivated in those countries. The olive industry, for
example, is even now being successfully developed by modern
methods in Asiatic and African sections, where the average annual
rainfall is under ten inches. Since 1881, under French management,
the dry-farm olive trees around Tunis have increased from 45,000
to 400,000 individuals. Mason and also Aaronsohn suggest as trees
that do well in the arid parts of the old world the so-called
"Chinese date" or JuJube tree, the sycamore fig, and the Carob
tree, which yields the "St. John's Bread" so dear to childhood.
Of this last tree, Aaronsolm says that twenty trees to the acre,
under a rainfall of twelve inches, will produce 8000 pounds of
fruit containing 40 per cent of sugar and 7 to 8 per cent of
protein. This surpasses the best harvest of alfalfa. Kearnley, who
has made a special study of dry-land olive culture in northern
Africa, states that in his belief a large variety of fruit trees
may be found which will do well under arid and semiarid
conditions, and may even yield more profit than the grains.
It is also said that many shade and ornamental and other useful
plants can be grown on dry-farms; as, for instance, locust, elm,
black walnut, silverpoplar, catalpa, live oak, black oak, yellow
pine, red spruce, Douglas fir, and cedar.
The secret of success in tree growing on dry-farms seems to lie,
first, in planting a few trees per acre,--the distance apart
should be twice the ordinary distance,--and, secondly, in applying
vigorously and unceasingly the established principles of soil
cultivation. In a soil stored deeply with moisture and properly
cultivated, most plants will grow. If the soil has not been
carefully fallowed before planting, it may be necessary to water
the young trees slightly during the first two seasons.
Small fruits have been tried on many farms with great success.
Plums, currants, and gooseberries have all been successful. Grapes
grow and yield well in many dry-farm districts, especially along
the warm foothills of the Great Basin. Tree growing on dry-farm
lands is not yet well established and, therefore, should be
undertaken with great care. Varieties accustomed to the climatic
environment should be chosen, and the principles outlined in the
preceding pages should be carefully used.
Potatoes
In recent years, potatoes have become one of the best dry-farm
crops. Almost wherever tried on lands under a rainfall of twelve
inches or more potatoes have given comparatively large yields.
To-day, the growing of dry-farm potatoes is becoming an important
industry. The principles of light seeding and thorough cultivation
are indispensable for success. Potatoes are well adapted for use
in rotations, where summer fallowing is not thought desirable.
Macdonald enumerates the following as the best varieties at
present used on dry-farms: Ohio, Mammoth, Pearl, Rural New Yorker,
and Burbank.
Miscellaneous
A further list of dry-farm crops would include representatives of
nearly all economic plants, most of them tried in small quantity
in various localities. Sugar beets, vegetables, bulbous plants,
etc., have all been grown without irrigation under dry-farm
conditions. Some of these will no doubt be found to be profitable
and will then be brought into the commercial scheme of
dry-farming.
Meanwhile, the crop problems of dry-farming demand that much
careful work be done in the immediate future by the agencies
having such work in charge. The best varieties of crops already in
profitable use need to be determined. More new plants from all
parts of the world need to be brought to this new dry-farm
territory and tried out. Many of the native plants need
examination with a view to their economic use. For instance, the
sego lily bulbs, upon which the Utah pioneers subsisted for
several seasons of famine, may possibly be made a cultivated crop.
Finally, it remains to be said that it is doubtful wisdom to
attempt to grow the more intensive crops on dry-farms. Irrigation
and dry-farming will always go together. They are supplementary
systems of agriculture in arid and semiarid regions. On the
irrigated lands should be grown the crops that require much labor
per acre and that in return yield largely per acre. New crops and
varieties should besought for the irrigated farms. On the
dry-farms should be grown the crops that can be handled in a large
way and at a small cost per acre, and that yield only moderate
acre returns. By such cooperation between irrigation and
dry-farming will the regions of the world with a scanty rainfall
become the healthiest, wealthiest, happiest, and most populous on
earth.
THE acre-yields of crops on dry-farms, even under the most
favorable methods of culture, are likely to be much smaller than
in humid sections with fertile soils. The necessity for frequent
fallowing or resting periods over a large portion of the dry-farm
territory further decreases the average annual yield. It does not
follow from this condition that dry-farming is less profitable
than humid- or irrigation-farming, for it has been fully
demonstrated that the profit on the investment is as high under
proper dry-farming as under any other similar generally adopted
system of farming in any part of the world. Yet the practice of
dry-farming would appear to be, and indeed would be, much more
desirable could the crop yield be increased. The discovery of any
condition which will offset the small annual yields is, therefore,
of the highest importance to the advancement of dry-farming. The
recognition of the superior quality of practically all crops grown
without irrigation under a limited rainfall has done much to
stimulate faith in the great profitableness of dry-farming. As the
varying nature of the materials used by man for food, clothing,
and shelter has become more clearly understood, more attention has
been given to the valuation of commercial products on the basis of
quality as well as of quantity. Sugar beets, for instance, are
bought by the sugar factories under a guarantee of a minimum sugar
content; and many factories of Europe vary the price paid
according to the sugar contained by the beets. The millers,
especially in certain parts of the country where wheat has
deteriorated, distinguish carefully between the flour-producing
qualities of wheats from various sections and fix the price
accordingly. Even in the household, information concerning the
real nutritive value of various foods is being sought eagerly, and
foods let down to possess the highest value in the maintenance of
life are displacing, even at a higher cost, the inferior products.
The quality valuation is, in fact, being extended as rapidly as
the growth of knowledge will permit to the chief food materials of
commerce. As this practice becomes fixed the dry-farmer will be
able to command the best market prices for his products, for it is
undoubtedly true that from the point of view of quality, dry-farm
food products may be placed safely in competition with any farm
products on the markets of the world.
Proportion of plant parts
It need hardly be said, after the discussions in the preceding
chapters, that the nature of plant growth is deeply modified by
the arid conditions prevailing in dry-farming. This shows itself
first in the proportion of the various plant parts, such as roots,
stems, leaves, and seeds. The root systems of dry-farm crops are
generally greatly developed, and it is a common observation that
in adverse seasons the plants that possess the largest and most
vigorous roots endure best the drouth and burning heat. The first
function of the leaves is to gather materials for the building and
strengthening of the roots, and only after this has been done do
the stems lengthen and the leaves thicken. Usually, the short
season is largely gone before the stem and leaf growth begins,
and, consequently, a somewhat dwarfed appearance is characteristic
of dry-farm crops. The size of sugar beets, potato tubers, and
such underground parts depends upon the available water and food
supply when the plant has established a satisfactory root and leaf
system. If the water and food are scarce, a thin beet results; if
abundant, a well-filled beet may result.
Dry-farming is characterized by a somewhat short season. Even if
good growing weather prevails, the decrease of water in the soil
has the effect of hastening maturity. The formation of flowers and
seed begins, therefore, earlier and is completed more quickly
under arid than under humid conditions. Moreover, and resulting
probably from the greater abundance of materials stored in the
root system, the proportion of heads to leaves and stems is
highest in dry-farm crops. In fact, it is a general law that the
proportion of heads to straw in grain crops increases as the water
supply decreases. This is shown very well even under humid or
irrigation conditions when different seasons or different
applications of irrigation water are compared. For instance, Hall
quotes from the Rothamsted experiments to the effect that in 1879,
which was a wet year (41 inches), the wheat crop yielded 38 pounds
of grain for every 100 pounds of straw; whereas, in 1893, which
was a dry year (23 inches), the wheat crop yielded 95 pounds of
grain to every 100 pounds of straw. The Utah station likewise has
established the same law under arid conditions. In one series of
experiments it was shown as an average of three years' trial that
a field which had received 22.5 inches of irrigation water
produced a wheat crop that gave 67 pounds of grain to every 100
pounds of straw; while another field which received only 7.5
inches of irrigation water produced a crop that gave 100 pounds of
grain for every 100 pounds of straw. Since wheat is grown
essentially for the grain, such a variation is of tremendous
importance. The amount of available water affects every part of
the plant. Thus, as an illustration, Carleton states that the per
cent of meat in oats grown in Wisconsin under humid conditions was
67.24, while in North Dakota, Kansas, and Montana, under arid and
semiarid conditions, it was 71.51. Similar variations of plant
parts may be observed as a direct result of varying the amount of
available water. In general then, it may be said that the roots of
dry-farm crops are well developed; the parts above ground somewhat
dwarfed; the proportion of seed to straw high, and the proportion
of meat or nutritive materials in the plant parts likewise high.
The water in dry-farm crops
One of the constant constituents of all plants and plant parts is
water. Hay, flour, and starch contain comparatively large
quantities of water, which can be removed only by heat. The water
in green plants is often very large. In young lucern, for
instance, it reaches 85 per cent, and in young peas nearly 90 per
cent, or more than is found in good cow's milk. The water so held
by plants has no nutritive value above ordinary water. It is,
therefore, profitable for the consumer to buy dry foods. In this
particular, again, dry-farm crops have a distinct advantage:
During growth there is not perhaps a great difference in the water
content of plants, due to climatic differences, but after harvest
the drying-out process goes on much more completely in dry-farm
than in humid districts. Hay, cured in humid regions, often
contains from 12 to 20 per cent of water; in arid climates it
contains as little as 5 per cent and seldom more than 12 per cent.
The drier hay is naturally more valuable pound for pound than the
moister hay, and a difference in price, based upon the difference
in water content, is already being felt in certain sections of the
West.
The moisture content of dry-farm wheat, the chief dry-farm crop,
is even more important. According to Wiley the average water
content of wheat for the United States is 10.62 per cent, ranging
from 15 to 7 per cent. Stewart and Greaves examined a large number
of wheats grown on the dry-farms of Utah and found that the
average per cent of water in the common bread varieties was 8.46
and in the durum varieties 8.89. This means that the Utah dry-farm
wheats transported to ordinary humid conditions would take up
enough water from the air to increase their weight one fortieth,
or 2.2 per cent, before they reached the average water content of
American wheats. In other words, 1,000,000 bushels of Utah
dry-farm wheat contain as much nutritive matter as 1,025,000
bushels of wheat grown and kept under humid conditions. This
difference should be and now is recognized in the prices paid. In
fact, shrewd dealers, acquainted with the dryness of dry-farm
wheat, have for some years bought wheat from the dry-farms at a
slightly increased price, and trusted to the increase in weight
due to water absorption in more humid climates for their profits.
The time should be near at hand when grains and similar products
should be purchased upon the basis of a moisture test.
While it is undoubtedly true that dry-farm crops are naturally
drier than those of humid countries, yet it must also be kept in
mind that the driest dry-farm crops are always obtained where the
summers are hot and rainless. In sections where the precipitation
comes chiefly in the spring and summer the difference would not be
so great. Therefore, the crops raised on the Great Plains would
not be so dry as those raised in California or in the Great Basin.
Yet, wherever the annual rainfall is so small as to establish
dry-farm conditions, whether it comes in the winter or summer, the
cured crops are drier than those produced under conditions of a
much higher rainfall, and dry farmers should insist that, so far
as possible in the future, sales be based on dry matter.
The nutritive substances in crops
The dry matter of all plants and plant parts consists of three
very distinct classes of substances: First, ash or the mineral
constituents. Ash is used by the body in building bones and in
supplying the blood with compounds essential to the various life
processes. Second, protein or the substances containing the
element nitrogen. Protein is used by the body in making blood,
muscle, tendons, hair, and nails, and under certain conditions it
is burned within the body for the production of heat. Protein is
perhaps the most important food constituent. Third,
non-nitrogenous substances, including fats, woody fiber, and
nitrogen-free extract, a name given to the group of sugars,
starehes, and related substances. These substances are used by the
body in the production of fat, and are also burned for the
production of heat. Of these valuable food constituents protein is
probably the most important, first, because it forms the most
important tissues of the body and, secondly, because it is less
abundant than the fats, starches, and sugars. Indeed, plants rich
in protein nearly always command the highest prices.
The composition of any class of plants varies considerably in
different localities and in different seasons. This may be due to
the nature of the soil, or to the fertilizer applied, though
variations in plant composition resulting from soil conditions are
comparatively small. The greater variations are almost wholly the
result of varying climate and water supply. As far as it is now
known the strongest single factor in changing the composition of
plants is the amount of water available to the growing plant.
Variations due to varying water
supply
The Utah station has conducted numerous experiments upon the
effect of water upon plant composition. The method in every case
has been to apply different amounts of water throughout the
growing season on contiguous plats of uniform land. [Lengthy table
deleated from this edition.] Even a casual study of . . . [the
results show] that the quantity of water used influenced the
composition of the plant parts. The ash and the fiber do not
appear to be greatly influenced, but the other constituents vary
with considerable regularity with the variations in the amount of
irrigation water. The protein shows the greatest variation. As the
irrigation water is increased, the percentage of protein
decreases. In the case of wheat the variation was over 9 per cent.
The percentage of fat and nitrogen-free extract, on the other
hand, becomes larger as the water increases. That is, crops grown
with little water, as in dry-farming, are rich in the important
flesh- and blood-forming substance protein, and comparatively poor
in fat, sugar, stareh, and other of the more abundant heat and
fat-producing substances. This difference is of tremendous
importance in placing dry-farming products on the food markets of
the world. Not only seeds, tubers, and roots show this variation,
but the stems and leaves of plants grown with little water are
found to contain a higher percentage of protein than those grown
in more humid climates.
The direct effect of water upon the composition of plants has been
observed by many students. For instance, Mayer, working in
Holland, found that, in a soil containing throughout the season 10
per cent of water, oats was produced containing 10.6 per cent of
protein; in soil containing 30 per cent of water, the protein
percentage was only 5.6 per cent, and in soil containing 70 per
cent of water, it was only 5.2 per cent. Carleton, in a study of
analyses of the same varieties of wheat grown in humid and
semi-arid districts of the United States, found that the
percentage of protein in wheat from the semiarid area was 14.4 per
cent as against 11.94 per cent in the wheat from the humid area.
The average protein content of the wheat of the United States is a
little more than 12 per cent; Stewart and Greaves found an average
of 16.76 per cent of protein in Utah dry-farm wheats of the common
bread varieties and 17.14 per cent in the durum varieties. The
experiments conducted at Rothamsted, England, as given by Hall,
confirm these results. For example, during 1893, a very dry year,
barley kernels contained 12.99 per cent of protein, while in 1894,
a wet, though free-growing year, the barley contained only 9.81
per cent of protein. Quotations might be multiplied confirming the
principle that crops grown with little water contain much protein
and little heat- and fat-producing substances.
Climate and composition
The general climate, especially as regards the length of the
growing season and naturally including the water supply, has a
strong effect upon the composition of plants. Carleton observed
that the same varieties of wheat grown at Nephi, Utah, contained
16.61 per cent protein; at Amarillo, Texas, 15.25 per cent; and at
McPherson, Kansas, a humid station, 13.04 per cent. This variation
is undoubtedly due in part to the varying annual precipitation
but, also, and in large part, to the varying general climatic
conditions at the three stations.
An extremely interesting and important experiment, showing the
effect of locality upon the composition of wheat kernels, is
reported by LeClerc and Leavitt. Wheat grown in 1905 in Kansas was
planted in 1906 in Kansas, California, and Texas In 1907 samples
of the seeds grown at these three points were planted side by side
at each of the three states All the crops from the three
localities were analyzed separately each year.
The results are striking and convincing. The original seed grown
in Kansas in 1905 contained 16.22 per cent of protein. The 1906
crop grown from this seed in Kansas contained 19.13 per cent
protein; in California, 10.38 percent; and in Texas,12.18 percent.
In 1907 the crop harvested in Kansas from the 1906 seed from these
widely separated places and of very different composition
contained uniformly somewhat more than 22 per cent of protein;
harvested in California, somewhat more than 11 per cent; and
harvested in Texas, about 18 per cent. In short, the composition
of wheat kernels is independent of the composition of the seed or
the nature of the soil, but depends primarily upon the prevailing
climatic conditions, including the water supply. The weight of the
wheat per bushel, that is, the average size and weight of the
wheat kernel, and also the hardness or flinty character of the
kernels, were strongly affected by the varying climatic
conditions. It is generally true that dry-farm grain weighs more
per bushel than grain grown under humid conditions; hardness
usually accompanies a high protein content and is therefore
characteristic of dry-farm wheat. These notable lessons teach the
futility of bringing in new seed from far distant places in the
hope that better and larger crops may be secured. The conditions
under which growth occurs determine chiefly the nature of the
crop. It is a common experience in the West that farmers who do
not understand this principle send to the Middle West for seed
corn, with the result that great crops of stalks and leaves with
no ears are obtained. The only safe rule for the dry-farmer to
follow is to use seed which has been grown for many years under
dry-farm conditions.
A reason for variation in
composition
It is possible to suggest a reason for the high protein content of
dry-farm crops. It is well known that all plants secure most of
their nitrogen early in the growing period. From the nitrogen,
protein is formed, and all young plants are, therefore, very rich
in protein. As the plant becomes older, little more protein is
added, but more and more carbon is taken from the air to form the
fats, starches, sugars, and other non-nitrogenous substances.
Consequently, the proportion or percentage of protein becomes
smaller as the plant becomes older. The impelling purpose of the
plant is to produce seed. Whenever the water supply begins to give
out, or the season shortens in any other way, the plant
immediately begins to ripen. Now, the essential effect of dry-farm
conditions is to shorten the season; the comparatively young
plants, yet rich in protein, begin to produce seed; and at
harvest, seed, and leaves, and stalks are rich in the flesh- and
blood-forming element of plants. In more humid countries plants
delay the time of seed production and thus enable the plants to
store up more carbon and thus reduce the percent of protein. The
short growing season, induced by the shortness of water, is
undoubtedly the main reason for the higher protein content and
consequently higher nutritive value of all dry-farm crops.
Nutritive value of dry-farm hay,
straw, and flour
All the parts of dry-farm crops are highly nutritious. This needs
to be more clearly understood by the dry-farmers. Dry-farm hay,
for instance, because of its high protein content, may be fed with
crops not so rich in this element, thereby making a larger profit
for the farmer. Dry-farm straw often has the feeding value of good
hay, as has been demonstrated by analyses and by feeding tests
conducted in times of hay scarcity. Especially is the header straw
of high feeding value, for it represents the upper and more
nutritious ends of the stalks. Dry-farm straw, therefore, should
be carefully kept and fed to animals instead of being scattered
over the ground or even burned as is too often the case. Only few
feeding experiments having in view the relative feeding value of
dry-farm crops have as yet been made, but the few on record agree
in showing the superior value of dry-farm crops, whether fed
singly or in combination.
The differences in the chemical composition of plants and plant
products induced by differences in the water-supply and climatic
environment appear in the manufactured products, such as flour,
bran, and shorts. Flour made from Fife wheat grown on the
dry-farms of Utah contained practically 16 per cent of protein,
while flour made from Fife wheat grown in Lorraine and the Middle
West is reported by the Maine Station as containing from 13.03 to
13.75 per cent of protein. Flour made from Blue Stem wheat grown
on the Utah dry-farms contained 15.52 per cent of protein; from
the same variety grown in Maine and in the Middle West 11.69 and
11.51 per cent of protein respectively. The moist and dry gluten,
the gliadin and the glutenin, all of which make possible the best
and most nourishing kinds of bread, are present in largest
quantity and best proportion in flours made from wheats grown
under typical dry-farm conditions. The by-products of the milling
process, likewise, are rich in nutritive elements.
Future Needs
It has already been pointed out that there is a growing tendency
to purchase food materials on the basis of composition. New
discoveries in the domains of plant composition and animal
nutrition and the improved methods of rapid and accurate valuation
will accelerate this tendency. Even now, manufacturers of food
products print on cartons and in advertising matter quality
reasons for the superior food values of certain articles. At least
one firm produces two parallel sets of its manufactured foods, one
for the man who does hard physical labor, and the other for the
brain worker. Quality, as related to the needs of the body,
whether of beast or man, is rapidly becoming the first question in
judging any food material. The present era of high prices makes
this matter even more important.
In view of this condition and tendency, the fact that dry-farm
products are unusually rich in the most valuable nutritive
materials is of tremendous importance to the development of
dry-farming. The small average yields of dry-farm crops do not
look so small when it is known that they command higher prices per
pound in competition with the larger crops of more humid climates.
More elaborate investigations should be undertaken to determine
the quality of crops grown in different dry-farm districts. As far
as possible each section, great or small, should confine itself to
the growing of a variety of each crop yielding well and possessing
the highest nutritive value. In that manner each section of the
great dry-farm territory would soon come to stand for some
dependable special quality that would compel a first-class market.
Further, the superior feeding value of dry-farm products should be
thoroughly advertised among the consumers in order to create a
demand on the markets for a quality valuation. A few years of such
systematic honest work would do much to improve the financial
basis of dry-farming.
All plants when carefully burned leave a portion of ash, ranging
widely in quantity, averaging about 5 per cent, and often
exceeding 10 per cent of the dry weight of the plant. This plant
ash represents inorganic substances taken from the soil by the
roots. In addition, the nitrogen of plants, averaging about 2 per
cent and often amounting to 4 per cent, which, in burning, passes
off in gaseous form, is also usually taken from the soil by the
plant roots. A comparatively large quantity of the plant is,
therefore, drawn directly from the soil. Among the ash ingredients
are many which are taken up by the plant simply because they are
present in the soil; others, on the other hand, as has been shown
by numerous classical investigations, are indispensable to plant
growth. If any one of these indispensable ash ingredients be
absent, it is impossible for a plant to mature on such a soil. In
fact, it is pretty well established that, providing the physical
conditions and the water supply are satisfactory, the fertility of
a soil depends largely upon the amount of available ash
ingredients, or plant-food.
A clear distinction must be made between the total and available
plant-food. The essential plant-foods often occur in insoluble
combinations, valueless to plants; only the plant-foods that are
soluble in the soil-water or in the juices of plant roots are of
value to plants. It is true that practically all soils contain all
the indispensable plant-foods; it is also true, however, that in
most soils they are present, as available plant-foods, in
comparatively small quantities. When crops are removed from the
land year after year, without any return being made, it naturally
follows that under ordinary conditions the amount of available
plant-food is diminished, with a strong probability of a
corresponding diminution in crop-producing power. In fact, the
soils of many of the older countries have been permanently injured
by continuous cropping, with nothing returned, practiced through
centuries. Even in many of the younger states, continuous cropping
to wheat or other crops for a generation or less has resulted in a
large decrease in the crop yield.
Practice and experiment have shown that such diminishing fertility
may be retarded or wholly avoided, first, by so working or
cultivating the soil as to set free much of the insoluble
plant-food and, secondly, by returning to the soil all or part of
the plant-food taken away. The recent development of the
commercial fertilizer industry is a response to this truth. It may
be said that, so far as the agricultural soils of the world are
now known, only three of the essential plant-foods are likely to
be absent, namely, potash, phosphoric acid, and nitrogen; of
these, by far the most important is nitrogen. The whole question
of maintaining the supply of plant-foods in the soil concerns
itself in the main with the supply of these three substances.
The persistent fertility of
dry-farms
In recent years, numerous farmers and some investigators have
stated that under dry-farm conditions the fertility of soils is
not impaired by cropping without manuring. This view has been
taken because of the well-known fact that in localities where
dry-farming has been practiced on the same soils from twenty-five
to forty-five years, without the addition of manures, the average
crop yield has not only failed to diminish, but in most cases has
increased. In fact, it is the almost unanimous testimony of the
oldest dry-farmers of the United States, operating under a
rainfall from twelve to twenty inches, that the crop yields have
increased as the cultural methods have been perfected. If any
adverse effect of the steady removal of plant-foods has occurred,
it has been wholly overshadowed by other factors. The older
dry-farms in Utah, for instance, which are among the oldest of the
country, have never been manured, yet are yielding better to-day
than they did a generation ago. Strangely enough, this is not true
of the irrigated farms, operating under like soil and climatic
conditions. This behavior of crop production under dry-farm
conditions has led to the belief that the question of soil
fertility is not an important one to dry-farmers. Nevertheless, if
our present theories of plant nutrition are correct, it is also
true that, if continuous cropping is practiced on our dry-farm
soils without some form of manuring, the time must come when the
productive power of the soils will be injured and the only
recourse of the farmer will be to return to the soils some of the
plant-food taken from it.
The view that soil fertility is not diminished by dry-farming
appears at first sight to be strengthened by the results obtained
by investigators who have made determinations of the actual
plant-food in soils that have long been dry-farmed. The sparsely
settled condition of the dry-farm territory furnishes as yet an
excellent opportunity to compare virgin and dry-farmed lands and
which frequently may be found side by side in even the older
dry-farm sections. Stewart found that Utah dry-farm soils,
cultivated for fifteen to forty years and never manured, were in
many cases richer in nitrogen than neighboring virgin lands.
Bradley found that the soils of the great dry-farm wheat belt of
Eastern Oregon contained, after having been farmed for a quarter
of a century, practically as much nitrogen as the adjoining virgin
lands. These determinations were made to a depth of eighteen
inches. Alway and Trumbull, on the other hand, found in a soil
from Indian Head, Saskatchewan, that in twenty-five years of
cultivation the total amount of nitrogen had been reduced about
one third, though the alternation of fallow and crop, commonly
practiced in dry-farming, did not show a greater loss of soil
nitrogen than other methods of cultivation. It must be kept in
mind that the soil of Indian Head contains from two to three times
as much nitrogen as is ordinarily found in the soils of the Great
Plains and from three to four times as much as is found in the
soils of the Great Basin and the High Plateaus. It may be assumed,
therefore, that the Indian Head soil was peculiarly liable to
nitrogen losses. Headden, in an investigation of the nitrogen
content of Colorado soils, has come to the conclusion that arid
conditions, like those of Colorado, favor the direct accumulation
of nitrogen in soils. All in all, the undiminished crop yield and
the composition of the cultivated fields lead to the belief that
soil-fertility problems under dry-farm conditions are widely
different from the old well-known problems under humid conditions.
Reasons for dry-farming fertility
It is not really difficult to understand why the yields and,
apparently, the fertility of dry-farms have continued to increase
during the period of recorded dry-farm history--nearly half a
century.
First, the intrinsic fertility of arid as compared with humid
soils is very high. (See Chapter V.) The production and removal of
many successive bountiful crops would not have as marked an effect
on arid as on humid soils, for both yield and composition change
more slowly on fertile soils. The natural extraordinarily high
fertility of dry-farm soils explains, therefore, primarily and
chiefly, the increasing yields on dry-farm soils that receive
proper cultivation.
The intrinsic fertility of arid soils is not alone sufficient to
explain the increase in plant-food which undoubtedly occurs in the
upper foot or two of cultivated dry-farm lands. In seeking a
suitable explanation of this phenomenon it must be recalled that
the proportion of available plant-food in arid soils is very
uniform to great depths, and that plants grown under proper
dry-farm conditions are deep rooted and gather much nourishment
from the lower soil layers. As a consequence, the drain of a heavy
crop does not fall upon the upper few feet as is usually the case
in humid soils. The dry-farmer has several farms, one upon the
other, which permit even improper methods of farming to go on
longer than would be the case on shallower soils.
The great depth of arid soils further permits the storage of rain
and snow water, as has been explained in previous chapters, to
depths of from ten to fifteen feet. As the growing season
proceeds, this water is gradually drawn towards the surface, and
with it much of the plant-food dissolved by the water in the lower
soil layers. This process repeated year after year results in a
concentration in the upper soil layers of fertility normally
distributed in the soil to the full depth reach by the
soil-moisture. At certain seasons, especially in the fall, this
concentration may be detected with greatest certainty. In general,
the same action occurs in virgin lands, but the methods of
dry-farm cultivation and cropping which permit a deeper
penetration of the natural precipitation and a freer movement of
the soil-water result in a larger quantity of plant-food reaching
the upper two or three feet from the lower soil depths. Such
concentration near the surface, when it is not excessive, favors
the production of increased yields of crops.
The characteristic high fertility and great depth of arid soils
are probably the two main factors explaining the apparent increase
of the fertility of dry-farms under a system of agriculture which
does not include the practice of manuring. Yet, there are other
conditions that contribute largely to the result. For instance,
every cultural method accepted in dry-farming, such as deep
plowing, fallowing, and frequent cultivation, enables the
weathering forces to act upon the soil particles. Especially is it
made easy for the air to enter the soil. Under such conditions,
the plant-food unavailable to plants because of its insoluble
condition is liberated and made available. The practice of
dry-farming is of itself more conducive to such accumulation of
available plant food than are the methods of humid agriculture.
Further, the annual yield of any crop under conditions of
dry-farming is smaller than under conditions of high rainfall.
Less fertility is, therefore, removed by each crop and a given
amount of available fertility is sufficient to produce a large
number of crops without showing signs of deficiency. The
comparatively small annual yield of dry-farm crops is emphasized
in view of the common practice of summer fallowing, which means
that the land is cropped only every other year or possibly two
years out of three. Under such conditions the yield in any one
year is cut in two to give an annual yield.
The use of the header wherever possible in harvesting dry-farm
grain also aids materially in maintaining soil fertility. By means
of the header only the heads of the grain are clipped off: the
stalks are left standing. In the fall, usually, this stubble is
plowed under and gradually decays. In the earlier dry-farm days
farmers feared that under conditions of low rainfall, the stubble
or straw plowed under would not decay, but would leave the soil in
a loose dry condition unfavorable for the growth of plants. During
the last fifteen years it has been abundantly demonstrated that if
the correct methods of dry farming are followed, so that a fair
balance of water is always found in the soil, even in the fall,
the heavy, thick header stubble may be plowed into the soil with
the certainty that it will decay and thus enrich the soil. The
header stubble contains a very large proportion of the nitrogen
that the crop has taken from the soil and more than half of the
potash and phosphoric acid. Plowing under the header stubble
returns all this material to the soil. Moreover, the bulk of the
stubble is carbon taken from the air. This decays, forming various
acid substances which act on the soil grains to set free the
fertility which they contain. At the end of the process of decay
humus is formed, which is not only a storehouse of plant-food, but
effective in maintaining a good physical condition of the soil.
The introduction of the header in dry-farming was one of the big
steps in making the practice certain and profitable.
Finally, it must be admitted that there are a great many more or
less poorly understood or unknown forces at work in all soils
which aid in the maintenance of soil-fertility. Chief among these
are the low forms of life known as bacteria. Many of these, under
favorable conditions, appear to have the power of liberating food
from the insoluble soil grains. Others have the power when settled
on the roots of leguminous or pod-bearing plants to fix nitrogen
from the air and convert it into a form suitable for the need of
plants. In recent years it has been found that other forms of
bacteria, the best known of which is azotobacter, have the power
of gathering nitrogen from the air and combining it for the plant
needs without the presence of leguminous plants. These
nitrogen-gathering bacteria utilize for their life processes the
organic matter in the soil, such as the decaying header stubble,
and at the same time enrich the soil by the addition of combined
nitrogen. Now, it so happens that these important bacteria require
a soil somewhat rich in lime, well aerated and fairly dry and
warm. These conditions are all met on the vast majority of our
dry-farm soils, under the system of culture outlined in this
volume. Hall maintains that to the activity of these bacteria must
be ascribed the large quantities of nitrogen found in many virgin
soils and probably the final explanation of the steady nitrogen
supply for dry farms is to be found in the work of the azatobacter
and related forms of low life. The potash and phosphoric acid
supply can probably be maintained for ages by proper methods of
cultivation, though the phosphoric acid will become exhausted long
before the potash. The nitrogen supply, however, must come from
without. The nitrogen question will undoubtedly soon be the one
before the students of dry-farm fertility. A liberal supply of
organic matter In the soil with cultural methods favoring the
growth of the nitrogen-gathering bacteria appears at present to be
the first solution of the nitrogen question. Meanwhile, the
activity of the nitrogen-gathering bacteria, like azotobacter, is
one of our best explanations of the large presence of nitrogen in
cultivated dry-farm soils.
To summarize, the apparent increase in productivity and plant-food
content of dry-farm soils can best be explained by a consideration
of these factors: (1) the intrinsically high fertility of the arid
soils; (2) the deep feeding ground for the deep root systems of
dry-farm crops; (3) the concentration of the plant food
distributed throughout the soil by the upward movement of the
natural precipitation stored in the soil; (4) the cultural methods
of dry-farming which enable the weathering agencies to liberate
freely and vigorously the plant-food of the soil grains; (5) the
small annual crops; (6) the plowing under of the header straw, and
(7) the activity of bacteria that gather nitrogen directly from
the air.
Methods of conserving
soil-fertility
In view of the comparatively small annual crops that characterize
dry-farming it is not wholly impossible that the factors above
discussed, if properly applied, could liberate the latent
plant-food of the soil and gather all necessary nitrogen for the
plants. Such an equilibrium, could it once be established, would
possibly continue for long periods of time, but in the end would
no doubt lead to disaster; for, unless the very cornerstone of
modern agricultural science is unsound, there will be ultimately a
diminution of crop producing power if continuous cropping is
practiced without returning to the soil a goodly portion of the
elements of soil fertility taken from it. The real purpose of
modern agricultural researeh is to maintain or increase the
productivity of our lands; if this cannot be done, modern
agriculture is essentially a failure. Dry-farming, as the newest
and probably in the future one of the greatest divisions of modern
agriculture, must from the beginning seek and apply processes that
will insure steadiness in the productive power of its lands.
Therefore, from the very beginning dry-farmers must look towards
the conservation of the fertility of their soils.
The first and most rational method of maintaining the fertility of
the soil indefinitely is to return to the soil everything that is
taken from it. In practice this can be done only by feeding the
products of the farm to live stock and returning to the soil the
manure, both solid and liquid, produced by the animals. This
brings up at once the much discussed question of the relation
between the live stock industry and dry-farming. While it is
undoubtedly true that no system of agriculture will be wholly
satisfactory to the farmer and truly beneficial to the state,
unless it is connected definitely with the production of live
stock, yet it must be admitted that the present prevailing
dry-farm conditions do not always favor comfortable animal life.
For instance, over a large portion of the central area of the
dry-farm territory the dry-farms are at considerable distances
from running or well water. In many cases, water is hauled eight
or ten miles for the supply of the men and horses engaged in
farming. Moreover, in these drier districts, only certain crops,
carefully cultivated, will yield profitably, and the pasture and
the kitchen garden are practical impossibilities from an economic
point of view. Such conditions, though profitable dry-farming is
feasible, preclude the existence of the home and the barn on or
even near the farm. When feed must be hauled many miles, the
profits of the live stock industry are materially reduced and the
dry-farmer usually prefers to grow a crop of wheat, the straw of
which may be plowed under the soil to the great advantage of the
following crop. In dry-farm districts where the rainfall is higher
or better distributed, or where the ground water is near the
surface, there should be no reason why dry-farming and live stock
should not go hand in hand. Wherever water is within reach, the
homestead is also possible. The recent development of the gasoline
motor for pumping purposes makes possible a small home garden
wherever a little water is available. The lack of water for
culinary purposes is really the problem that has stood between the
joint development of dry-farming and the live stock industry. The
whole matter, however, looks much more favorable to-day, for the
efforts of the Federal and state governments have succeeded in
discovering numerous subterranean sources of water in dry-farm
districts. In addition, the development of small irrigation
systems in the neighborhood of dry-farm districts is helping the
cause of the live stock industry. At the present time, dry-farming
and the live stock industry are rather far apart, though
undoubtedly as the desert is conquered they will become more
closely associated. The question concerning the best maintenance
of soil-fertility remains the same; and the ideal way of
maintaining fertility is to return to the soil as much as is
possible of the plant-food taken from it by the crops, which can
best be accomplished by the development of the business of keeping
live stock in connection with dry-farming.
If live stock cannot be kept on a dry-farm, the most direct method
of maintaining soil-fertility is by the application of commercial
fertilizers. This practice is followed extensively in the Eastern
states and in Europe. The large areas of dry-farms and the high
prices of commercial fertilizers will make this method of manuring
impracticable on dry-farms, and it may be dismissed from thought
until such a day as conditions, especially with respect to price
of nitrates and potash, are materially changed.
Nitrogen, which is the most important plant-food that may be
absent from dry-farm soils, may be secured by the proper use of
leguminous crops. All the pod-bearing plants commonly cultivated,
such as peas, beans, vetch, clover, and lucern, are able to secure
large quantities of nitrogen from the air through the activity of
bacteria that live and grow on the roots of such plants. The
leguminous crop should be sown in the usual way, and when it is
well past the flowering stage should be plowed into the ground.
Naturally, annual legumes, such as peas and beans, should be used
for this purpose. The crop thus plowed under contains much
nitrogen, which is gradually changed into a form suitable for
plant assimilation. In addition, the acid substances produced in
the decay of the plants tend to liberate the insoluble plant-foods
and the organic matter is finally changed into humus. In order to
maintain a proper supply of nitrogen in the soil the dry-farmer
will probably soon find himself obliged to grow, every five years
or oftener, a crop of legumes to be plowed under.
Non-leguminous crops may also be plowed under for the purpose of
adding organic matter and humus to the soil, though this has
little advantage over the present method of heading the grain and
plowing under the high stubble. The header system should be
generally adopted on wheat dry-farms. On farms where corn is the
chief crop, perhaps more importance needs to he given to the
supply of organic matter and humus than on wheat farms. The
occasional plowing under of leguminous crops would he the most
satisfactory method. The persistent application of the proper
cultural methods of dry-farming will set free the most important
plant-foods, and on well-cultivated farms nitrogen is the only
element likely to be absent in serious amounts.
The rotation of crops on dry-farms is usually advocated in
districts like the Great Plains area, where the annual rainfall is
over fifteen inches and the major part of the precipitation comes
in spring and summer. The various rotations ordinarily include one
or more crops of small grains, a hoed crop like corn or potatoes,
a leguminous crop, and sometimes a fallow year. The leguminous
crop is grown to secure a fresh supply of nitrogen; the hoed crop,
to enable the air and sunshine to act thoroughly on the soil
grains and to liberate plant-food, such as potash and phosphoric
acid; and the grain crops to take up plant-food not reached by the
root systems of the other plants. The subject of proper rotation
of crops has always been a difficult one, and very little
information exists on it as practiced on dry-farms. Chilcott has
done considerable work on rotations in the Great Plains district,
hut he frankly admits that many years of trial will he necessary
for the elucidation of trustworthy principles. Some of the best
rotations found by Chilcott up to the present are:--
Corn--Wheat--Oats
Barley--Oats--Corn
Fallow--Wheat--Oats
Rosen states that rotation is very commonly practiced in the dry
sections of southern Russia, usually including an occasional
Summer fallow. As a type of an eight-year rotation practiced at
the Poltava Station, the following is given: (1) Summer tilled and
manured; (2) winter wheat; (3) hoed crop; (4) spring wheat; (5)
summer fallow; (6) winter rye; (7) buckwheat or an annual legume;
(8) oats. This rotation, it may be observed, includes the grain
crop, hoed crop, legume, and fallow every four years.
As has been stated elsewhere, any rotation in dry-farming which
does not include the summer fallow at least every third or fourth
year is likely to be dangerous In years of deficient rainfall.
This review of the question of dry-farm fertility is intended
merely as a forecast of coming developments. At the present time
soil-fertility is not giving the dry-farmers great concern, but as
in the countries of abundant rainfall the time will come when it
will be equal to that of water conservation, unless indeed the
dry-farmers heed the lessons of the past and adopt from the start
proper practices for the maintenance of the plant-food stored in
the soil. The principle explained in Chapter IX, that the amount
of water required for the production of one pound of water
diminishes as the fertility increases, shows the intimate
relationship that exists between the soil-fertility and the
soil-water and the importance of maintaining dry-farm soils at a
high state of fertility.
CHEAP land and relatively small acre yields characterize
dry-farming. Consequently Iarger areas must be farmed for a given
return than in humid farming, and the successful pursuit of
dry-farming compels the adoption of methods that enable a man to
do the largest amount of effective work with the smallest
expenditure of energy. The careful observations made by Grace, in
Utah, lead to the belief that, under the conditions prevailing in
the intermountain country, one man with four horses and a
sufficient supply of machinery can farm 160 acres, half of which
is summer-fallowed every year; and one man may, in favorable
seasons under a carefully planned system, farm as much as 200
acres. If one man attempts to handle a larger farm, the work is
likely to be done in so slipshod a manner that the crop yield
decreases and the total returns are no larger than if 200 acres
had been well tilled.
One man with four horses would be unable to handle even 160 acres
were it not for the possession of modern machinery; and
dry-farming, more than any other system of agriculture, is
dependent for its success upon the use of proper implements of
tillage. In fact, it is very doubtful if the reclamation of the
great arid and semiarid regions of the world would have been
possible a few decades ago, before the invention and introduction
of labor-saving farm machinery. It is undoubtedly further a fact
that the future of dry-farming is closely bound up with the
improvements that may be made in farm machinery. Few of the
agricultural implements on the market to-day have been made
primarily for dry-farm conditions. The best that the dry-farmer
can do is to adapt the implements on the market to his special
needs. Possibly the best field of investigation for the experiment
stations and inventive minds in the arid region is farm mechanics
as applied to the special needs of dry-farming.
Clearing and breaking
A large portion of the dry-farm territory of the United States is
covered with sagebrush and related plants. It is always a
difficult and usually an expensive problem to clear sagebrush
land, for the shrubs are frequently from two to six feet high,
correspondingly deep-rooted, with very tough wood. When the soil
is dry, it is extremely difficult to pull out sagebrush, and of
necessity much of the clearing must be done during the dry season.
Numerous devices have been suggested and tried for the purpose of
clearing sagebrush land. One of the oldest and also one of the
most effective devices is two parallel railroad rails connected
with heavy iron chains and used as a drag over the sagebrush land.
The sage is caught by the two rails and torn out of the ground.
The clearing is fairly complete, though it is generally necessary
to go over the ground two or three times before the work is
completed. Even after such treatment a large number of sagebrush
clumps, found standing over the field, must be grubbed up with the
hoe. Another and effective device is the so-called "mankiller."
This implement pulls up the sage very successfully and drops it at
certain definite intervals. It is, however, a very dangerous
implement and frequently results in injury to the men who work it.
Of recent years another device has been tried with a great deal of
success. It is made like a snow plow of heavy railroad irons to
which a number of large steel knives have been bolted. Neither of
these implements is wholly satisfactory, and an acceptable machine
for grubbing sagebrush is yet to be devised. In view of the large
expense attached to the clearing of sagebrush land such a machine
would be of great help in the advancement of dry-farming.
Away from the sagebrush country the virgin dry-farm land is
usually covered with a more or less dense growth of grass, though
true sod is seldom found under dry-farm conditions. The ordinary
breaking plow, characterized by a long sloping moldboard, is the
best known implement for breaking all kinds of sod. (See Fig. 7a
a.) Where the sod is very light, as on the far western prairies,
the more ordinary forms of plows may be used. In still other
sections, the dry-farm land is covered with a scattered growth of
trees, frequently pinion pine and cedars, and in Arizona and New
Mexico the mesquite tree and cacti are to be removed. Such
clearing has to be done in accordance with the special needs of
the locality.
Plowing
Plowing, or the turning over of the soil to a depth of from seven
to ten inches for every crop, is a fundamental operation of
dry-farming. The plow, therefore, becomes one of the most
important implements on the dry-farm. Though the plow as an
agricultural implement is of great antiquity, it is only within
the last one hundred years that it has attained its present
perfection. It is a question even to-day, in the minds of a great
many students, whether the modern plow should not be replaced by
some machine even more suitable for the proper turning and
stirring of the soil. The moldboard plow is, everything
considered, the most satisfactory plow for dry-farm purposes. A
plow with a moldboard possessing a short abrupt curvature is
generally held to be the most valuable for dry-farm purposes,
since it pulverizes the soil most thoroughly, and in dry-farming
it is not so important to turn the soil over as to crumble and
loosen it thoroughly. Naturally, since the areas of dry-farms are
very large, the sulky or riding plow is the only kind to be used.
The same may be said of all other dry-farm implements. As far as
possible, they should be of the riding kind since in the end it
means economy from the resulting saving of energy.
The disk plow has recently come into prominent use throughout the
land. It consists, as is well known, of one or more large disks
which are believed to cause a smaller draft, as they cut into the
ground, than the draft due to the sliding friction upon the
moldboard. Davidson and Chase say, however, that the draft of a
disk plow is often heavier in proportion to the work done and the
plow itself is more clumsy than the moldboard plow. For ordinary
dry-farm purposes the disk plow has no advantage over the modern
moldboard plow. Many of the dry-farm soils are of a heavy clay and
become very sticky during certain seasons of the year. In such
soils the disk plow is very useful. It is also true that dry-farm
soils, subjected to the intense heat of the western sun become
very hard. In the handling of such soils the disk plow has been
found to be most useful. The common experience of dry-farmers is
that when sagebrush lands have been the first plowing can be most
successfully done with the disk plow, but that after. the first
crop has been harvested, the stubble land can be best handled with
the moldboard plow. All this, however, is yet to be subjected to
further tests.
While subsoiling results in a better storage reservoir for water
and consequently makes dry-farming more secure, yet the high cost
of the practice will probably never make it popular. Subsoiling is
accomplished in two ways: either by an ordinary moldboard plow
which follows the plow in the plow furrow and thus turns the soil
to a greater depth, or by some form of the ordinary subsoil plow.
In general, the subsoil plow is simply a vertical piece of cutting
iron, down to a depth of ten to eighteen inches, at the bottom of
which is fastened a triangular piece of iron like a shovel, which,
when pulled through the ground, tends to loosen the soil to the
full depth of the plow.
The subsoil plow does not turn the soil; it simply loosens the
soil so that the air and plant roots can penetrate to greater
depths.
In the choice of plows and their proper use the dryfarmer must be
guided wholly by the conditions under which he is working. It is
impossible at the present time to lay down definite laws stating
what plows are best for certain soils. The soils of the arid
region are not well enough known, nor has the relationship between
the plow and the soil been sufficiently well established. As above
remarked, here is one of the great fields for investigation for
both scientific and practical men for years to come.
Making and maintaining a
soil-mulch
After the land has been so well plowed that the rains can enter
easily, the next operation of importance in dry-farming is the
making and maintaining of a soil-mulch over the ground to prevent
the evaporation of water from the soil. For this purpose some form
of harrow is most commonly used. The oldest and best-known harrow
is the ordinary smoothing harrow, which is composed of iron or
steel teeth of various shapes set in a suitable frame. (See Fig.
79.) For dry-farm purposes the implement must be so made as to
enable the farmer to set the harrow teeth to slant backward or
forward. It frequently happens that in the spring the grain is too
thick for the moisture in the soil, and it then becomes necessary
to tear out some of the young plants. For this purpose the harrow
teeth are set straight or forward and the crop can then be thinned
effectively. At other times it may be observed in the spring that
the rains and winds have led to the formation of a crust over the
soil, which must be broken to let the plants have full freedom of
growth and development. This is accomplished by slanting the
harrow teeth backward, and the crust may then be broken without
serious injury to the plants. The smoothing harrow is a very
useful implement on the dry-farm. For following the plow, however,
a more useful implement is the disk harrow, which is a
comparatively recent invention. It consists of a series of disks
which may be set at various angles with the line of traction and
thus be made to turn over the soil while at the same time
pulverizing it. The best dry-farm practice is to plow in the fall
and let the soil lie in the rough during the winter months. In the
spring the land is thoroughly disked and reduced to a fine
condition. Following this the smoothing harrow is occasionally
used to form a more perfect mulch. When seeding is to be done
immediately after plowing, the plow is followed by the disk
harrow, and that in turn is followed by the smoothing harrow. The
ground is then ready for seeding. The disk harrow is also used
extensively throughout the summer in maintaining a proper mulch.
It does its work more effectively than the ordinary smoothing
harrow and is, therefore, rapidly displacing all other forms of
harrows for the purpose of maintaining a layer of loose soil over
the dry-farm. There are several kinds of disk harrows used by
dry-farmers. The full disk is, everything considered, the most
useful. The cutaway harrow is often used in cultivating old
alfalfa land; the spade disk harrow has a very limited application
in dry-farming; and the orchard disk harrow is simply a
modlfication of the full disk harrow whereby the farmer is able to
travel between the rows of trees and so to cultivate the soil
under the branches of the trees without injuring the leaves or
fruit.
One of the great difficulties in dry-farming concerns itself with
the prevention of the growth of weeds or volunteer crops. As has
been explained in previous chapters, weeds require as much water
for their growth as wheat or other useful crops. During the fallow
season, the farmer is likely to be overtaken by the weeds and lose
much of the value of the fallow by losing soil-moisture through
the growth of weeds. Under the most favorable conditions weeds are
difficult to handle. The disk harrow itself is not effective. The
smoothing harrow is of less value. There is at the present time
great need for some implement that will effectively destroy young
weeds and prevent their further growth. Attempts are being made to
invent such implements, but up to the present without great
success. Hogenson reports the finding of an implement on a western
dry-farm constructed by the farmer himself which for a number of
years has shown itself of high efficiency in keeping the dry-farm
free from weeds. Several improved modifications of this implement
have been made and tried out on the famous dry-farm district at
Nephi, Utah, and with the greatest success. Hunter reports a
similar implement in common use on the dry-farms of the Columbia
Basin. Spring tooth harrows are also used in a small way on the
dry-farms.
They have no special advantage over the smoothing harrow or the
disk harrow, except in places where the attempt is made to
cultivate the soil between the rows of wheat. The curved knife
tooth harrow is scareely ever used on dry-farms. It has some value
as a pulverizer, but does not seem to have any real advantage over
the ordinary disk harrow.
Cultivators for stirring the land on which crops are growing are
not used extensively on dry-farms. Usually the spring tooth harrow
is employed for this work. In dry-farm sections, where corn is
grown, the cultivator is frequently used throughout the season.
Potatoes grown on dry-farms should be cultivated throughout the
season, and as the potato industry grows in the dry-farm territory
there will be a greater demand for suitable cultivators. The
cultivators to be used on dry-farms are all of the riding kind.
They should be so arranged that the horse walking between two rows
carries a cultivator that straddles several rows of plants and
cultivates the soil between. Disks, shovels, or spring teeth may
be used on cultivators. There is a great variety on the market,
and each farmer will have to choose such as meet most definitely
his needs.
The various forms of harrows and cultivators are of the greatest
importance in the development of dry-farming. Unless a proper
mulch can be kept over the soil during the fallow season, and as
far as possible during the growing season, first-class crops
cannot be fully respected.
The roller is occasionally used in dry-farming, especially in the
uplands of the Columbia Basin. It is a somewhat dangerous
implement to use where water conservation is important, since the
packing resulting from the roller tends to draw water upward from
the lower soil layers to be evaporated into the air. Wherever the
roller is used, therefore, it should be followed immediately by a
harrow. It is valuable chiefly in the localities where the soil is
very loose and light and needs packing around the seeds to permit
perfect germination.
Subsurface packing
The subsurface packer invented by Campbell is [shown in Figure
83--not shown--ed.]. The wheels of this machine eighteen inches in
diameter, with rims one inch thick at the inner part, beveled two
and a half inches to a sharp outer edge, are placed on a shaft,
five inches apart. In practice about five hundred pounds of weight
are added.
This machine, according to Campbell, crowds a one-inch wedge into
every five inches of soil with a lateral and a downward pressure
and thus packs firmly the soil near the bottom of the plow-furrow.
Subsurface packing aims to establish full capillary connection
between the plowed upper soil and the undisturbed lower
soil-layer; to bring the moist soil in close contact with the
straw or organic litter plowed under and thus to hasten
decomposition, and to provide a firm seed bed.
The subsurface packer probably has some value where the plowed
soil containing the stubble is somewhat loose; or on soils which
do not permit of a rapid decay of stubble and other organic matter
that may be plowed under from season to season. On such soils the
packing tendency of the subsurface packer may help prevent loss of
soil water, and may also assist in furnishing a more uniform
medium through which plant roots may force their way. For all
these purposes, the disk is usually equally efficient.
Sowing
It has already been indicated in previous chapters that proper
sowing is one of the most important operations of the dry-farm,
quite comparable in importance with plowing or the maintaining of
a mulch for retaining soil-moisture. The old-fashioned method of
broadcasting has absolutely no place on a dry-farm. The success of
dry-farming depends entirely upon the control that the farmer has
of all the operations of the farm. By broadcasting, neither the
quantity of seed used nor the manner of placing the seed in the
ground can be regulated. Drill culture, therefore, introduced by
Jethro Tull two hundred years ago, which gives the farmer full
control over the process of seeding, is the only system to be
used. The numerous seed drills on the market all employ the same
principles. Their variations are few and simple. In all seed
drills the seed is forced into tubes so placed as to enable the
seed to fall into the furrows in the ground. The drills themselves
are distinguished almost wholly by the type of the furrow opener
and the covering devices which are used. The seed furrow is opened
either by a small hoe or a so-called shoe or disk. At the present
time it appears that the single disk is the coming method of
opening the seed furrow and that the other methods will gradually
disappear. As the seed is dropped into the furrow thus made it is
covered by some device at the rear of the machine. One of the
oldest methods as well as one of the most satisfactory is a series
of chains dragging behind the drill and covering the furrow quite
completely. It is, however, very desirable that the soil should be
pressed carefully around the seed so that germination may begin
with the least difficulty whenever the temperature conditions are
right. Most of the drills of the day are, therefore, provided with
large light wheels, one for each furrow, which press lightly upon
the soil and force the soil into intimate contact with the seed
The weakness of such an arrangement is that the soil along the
drill furrows is left somewhat packed, which leads to a ready
escape of the soil-moisture. Many of the drills are so arranged
that press wheels may be used at the pleasure of the farmer. The
seed drill is already a very useful implement and is rapidly being
made to meet the special requirements of the dry-farmer. Corn
planters are used almost exclusively on dry-farms where corn is
the leading crop. In principle they are very much the same as the
press drills. Potatoes are also generally planted by machinery.
Wherever seeding machinery has been constructed based upon the
principles of dry-farming, it is a very advantageous adjunct to
the dry-farm.
Harvesting
The immense areas of dry-farms are harvested almost wholly by the
most modern machinery. For grain, the harvester is used almost
exclusively in the districts where the header cannot be used, but
wherever conditions permit, the header is and should be used. It
has been explained in previous chapters how valuable the tall
header stubble is when plowed under as a means of maintaining the
fertility of the soil. Besides, there is an ease in handling the
header which is not known with the harvester. There are times when
the header leads to some waste as, for instance, when the wheat is
very low and heads are missed as the machine passes over the
ground. In many sections of the dry-farm territory the climatic
conditions are such that the wheat cures perfectly while still
standing. In such places the combined harvester and thresher is
used. The header cuts off the heads of the grain, which are passed
up into the thresher, and bags filled with threshed grain are
dropped along the path of the machine, while the straw is
scattered over the ground. Wherever such a machine can be used, it
has been found to be economical and satisfactory. Of recent years
corn stalks have been used to better advantage than in the past,
for not far from one half of the feeding value of the corn crop is
in the stalks, which up to a few years ago were very largely
wasted. Corn harvesters are likewise on the market and are quite
generally used. It was manifestly impossible on large places to
harvest corn by hand and large corn harvesters have, therefore,
been made for this purpose.
Steam and other motive power
Recently numerous persons have suggested that the expense of
running a dry-farm could be materially reduced by using some
motive power other than horses. Steam, gasoline, and electricity
have all been suggested. The steam traction engine is already a
fairly well-developed machine and it has been used for plowing
purposes on many dry-farms in nearly all the sections of the
dry-farm territory. Unfortunately, up to the present it has not
shown itself to be very satisfactory. First of all it is to be
remembered that the principles of dry-farming require that the
topsoil be kept very loose and spongy. The great traction engines
have very wide wheels of such tremendous weight that they press
down the soil very compactly along their path and in that way
defeat one of the important purposes of tillage. Another objection
to them is that at present their construction is such as to result
in continual breakages. While these breakages in themselves are
small and inexpensive, they mean the cessation of all farming
operations during the hour or day required for repairs. A large
crew of men is thus left more or less idle, to the serious injury
of the work and to the great expense of the owner. Undoubtedly,
the traction engine has a place in dry-farming, but it has not yet
been perfected to such a degree as to make it satisfactory. On
heavy soils it is much more useful than on light soils. When the
traction engine works satisfactorily, plowing may be done at a
cost considerably lower than when horses are employed.
In England, Germany, and other European countries some of the
difficulties connected with plowing have been overcome by using
two engines on the two opposite sides of a field. These engines
move synchronously together and, by means of large cables, plows,
harrows, or seeders, are pulled back and forth over the field.
This method seems to give good satisfaction on many large estates
of the old world. Macdonald reports that such a system is in
successful operation in the Transvaal in South Africa and is doing
work there at a very knew cost. The large initial cost of such a
system will, of course, prohibit its use except on the very large
farms that are being established in the dry-farm territory.
Gasoline engines are also being tried out, but up to date they
have not shown themselves as possessing superior advantages over
the steam engines. The two objections to them are the same as to
the steam engine: first, their great weight, which compresses in a
dangerous degree the topsoil and, secondly, the frequent
breakages, which make the operation slow and expensive.
Over a great part of the West, water power is very abundant and
the suggestion has been made that the electric energy which can be
developed by means of water power could be used in the cultural
operations of the dry-farm. With the development of the trolley
car which does not run on rails it would not seem impossible that
in favorable localities electricity could be made to serve the
farmer in the mechanical tillage of the dry-farm.
The substitution of steam and other energy for horse power is yet
in the future. Undoubtedly, it will come, but only as improvements
are made in the machines. There is here also a great field for
being of high service to the farmers who are attempting to reclaim
the great deserts of the world. As stated at the beginning of this
chapter, dry-farming would probably have been an
impossibilityfifty or a hundred years ago because of the absence
of suitable machinery. The future of dry-farming rests almost
wholly, so far as its profits are concerned, upon the development
of new and more suitable machinery for the tillage of the soil in
accordance with the established principles of dry-farming.
Finally, the recommendations made by Merrill may here be inserted.
A dry-farmer for best work should be supplied with the following
implements in addition to the necessary wagons and hand tools:--
One Plow.
One Disk.
One Smoothing Harrow.
One Drill Seeder.
One Harvester or Header.
One Mowing Machine.
IRRIGATION-farming and dry-farming are both systems of agriculture
devised for the reclamation of countries that ordinarily receive
an annual rainfall of twenty inches or less. Irrigation-farming
cannot of itself reclaim the arid regions of the world, for the
available water supply of arid countries when it shall have been
conserved in the best possible way cannot be made to irrigate more
than one fifth of the thirsty land. This means that under the
highest possible development of irrigation, at least in the United
States, there will be five or six acres of unirrigated or dry-farm
land for every acre of irrigated land. Irrigation development
cannot possibly, therefore, render the dry-farm movement
valueless. On the other hand, dry-farming is furthered by the
development of irrigation farming, for both these systems of
agriculture are characterized by advantages that make irrigation
and dry-farming supplementary to each other in the successful
development of any arid region.
Under irrigation, smaller areas need to be cultivated for the same
crop returns, for it has been amply demonstrated that the acre
yields under proper irrigation are very much larger than the best
yields under the most careful system of dry-farming. Secondly, a
greater variety of crops may be grown on the irrigated farm than
on the dry-farm. As has already been shown in this volume, only
certain drouth resistant crops can be grown profitably upon
dry-farms, and these must be grown under the methods of extensive
farming. The longer growing crops, including trees, succulent
vegetables, and a variety of small fruits, have not as yet been
made to yield profitably under arid conditions without the
artificial application of water. Further, the irrigation-farmer is
not largely dependent upon the weather and, therefore, carries on
this work with a feeling of greater security. Of course, it is
true that the dry years affect the flow of water in the canals and
that the frequent breaking of dams and canal walls leaves the
farmer helpless in the face of the blistering heat. Yet, all in
all, a greater feeling of security is possessed by the irrigation
farmer than by the dry-farmer.
Most important, however, are the temperamental differences in men
which make some desirous of giving themselves to the cultivation
of a small area of irrigated land under intensive conditions and
others to dry-farming under extensive conditions. In fact, it is
being observed in the arid region that men, because of their
temperamental differences, are gradually separating into the two
classes of irrigation-farmers and dry-farmers. The dry-farms of
necessity cover much larger areas than the irrigated farms. The
land is cheaper and the crops are smaller. The methods to be
applied are those of extensive farming. The profits on the
investment also appear to be somewhat larger. The very necessity
of pitting intellect against the fierceness of the drouth appears
to have attracted many- men to the dry-farms. Gradually the
certainty of producing crops on dry-farms from season to season is
becoming established, and the essential difference between the two
kinds of farming in the arid districts will then he the difference
between intensive and extensive methods of culture. Men will be
attracted to one or other of these systems of agriculture
according to their personal inclinations.
The scarcity of water
For the development of a well-rounded commonwealth in an arid
region it is, of course) indispensable that irrigation be
practiced, for dry-farming of itself will find it difficult to
build up populous cities and to supply the great variety of crops
demanded by the modern family. In fact, one of the great problems
before those engaged in the development of dry-farming at present
is the development of homesteads in the dry-farms. A homestead is
possible only where there is a sufficient amount of free water
available for household and stock purposes. In the portion of the
dry-farm territory where the rainfall approximates twenty inches,
this problem is not so very difficult, since ground water may be
reached easily. In the drier portions, however, where the rainfall
is between ten and fifteen inches, the problem is much more
important. The conditions that bring the district under the
dry-farm designation imply a scarcity of water. On few dry-farms
is water available for the needs of the household and the barns.
In the Rocky Mountain states numerous dry-farms have been
developed from seven to fifteen miles from the nearest source of
water, and the main expense of developing these farms has been the
hauling of water to the farms to supply the needs of the men and
beasts at work on them. Naturally, it is impossible to establish
homesteads on the dry-farms unless at least a small supply of
water is available; and dry-farming will never he what it might be
unless happy homes can be established upon the farms in the arid
regions that grow crops without irrigation. To make a dry-farm
homestead possible enough water must be available, first of all,
to supply the culinary needs of the household. This of itself is
not large and, as will be shown hereafter, may in most cases be
obtained. However, in order that the family may possess proper
comforts, there should be around the homestead trees, and shrubs,
and grasses, and the family garden. To secure these things a
certain amount of irrigation water is required. It may be added
that dry-farms on which such homesteads are found as a result of
the existence of a small supply of irrigation water are much more
valuable, in case of sale, than equally good farms without the
possibility of maintaining homesteads. Moreover, the distinct
value of irrigation in producing a large acre yield makes it
desirable for the farmer to use all the water at his disposal for
irrigation purposes. No available water should be allowed to flow
away unused.
Available surface water
The sources of water for dry-farms fall readily into classes:
surface waters and subterranean waters. The surface waters,
wherever they may be obtained, are generally the most profitable.
The simplest method of obtaining water in an irrigated region is
from some irrigation canal. In certain districts of the
intermountain region where the dry farms lie above the irrigation
canals and the irrigated lands below, it is comparatively easy for
the farmers to secure a small but sufficient amount of water from
the canal by the use of some pumping device that will force the
water through the pipes to the homestead. The dry-farm area that
may be so supplied by irrigation canals is, however, very limited
and is not to be considered seriously in connection with the
problem.
A much more important method, especially in the mountainous
districts, is the utilization of the springs that occur in great
numbers over the whole dry-farm territory. Sometimes these springs
are very small indeed, and often, after development by tunneling
into the side of the hill, yield only a trifling flow. Yet, when
this water is piped to the homestead and allowed to accumulate in
small reservoirs or cisterns, it may be amply sufficient for the
needs of the family and the live stock, besides having a surplus
for the maintenance of the lawn, the shade trees, and the family
garden. Many dry-farmers in the intermountain country have piped
water seven or eight miles from small springs that were considered
practically worthless and thereby have formed the foundations for
small village communities.
Of perhaps equal importance with the utilization of the naturally
occurring springs is the proper conservation of the flood waters.
As has been stated before, arid conditions allow a very large loss
of the natural precipitation as run-off. The numerous gullies that
characterize so many parts of the dry-farm territory are evidences
of the number and vigor of the flood waters. The construction of
small reservoirs in proper places for the purpose of catching the
flood waters will usually enable the farmer to supply himself with
all the water needed for the homestead. Such reservoirs may
already be found in great numbers scattered over the whole western
America. As dry-farming increases their numbers will also
increase.
When neither canals, nor springs, nor flood waters are available
for the supply of water, it is yet possible to obtain a limited
supply by so arranging the roof gutters on the farm buildings that
all the water that falls on the roofs is conducted through the
spouts into carefully protected cisterns or reservoirs. A house
thirty by thirty feet, the roof of which is so constructed that
all that water that falls upon it is carried into a cistern will
yield annually under a a rainfall of fifteen inches a maximum
amount of water equivalent to about 8800 gallons. Allowing for the
unavoidable waste due to evaporation, this will yield enough to
supply a household and some live stock with the necessary water.
In extreme cases this has been found to be a very satisfactory
practice, though it is the one to be resorted to only in case no
other method is available.
It is indispensable that some reservoir be provided to hold the
surface water that may be obtained until the time it may be
needed. The water coming constantly from a spring in summer should
be applied to crops only at certain definite seasons of the year.
The flood waters usually come at a time when plant growth is not
active and irrigation is not needed.
The rainfall also in many districts comes most largely at seasons
of no or little plant growth. Reservoirs must, therefore, be
provided for the storing of the water until the periods when it is
demanded by crops. Cement-lined cisterns are quite common, and in
many places cement reservoirs have been found profitable. In other
places the occurrence of impervious clay has made possible the
establishment and construction of cheap reservoirs. The skillful
and permanent construction of reservoirs is a very important
subject. Reservoir building should be undertaken only after a
careful study of the prevailing conditions and under the advice of
the state or government officials having such work in charge. In
general, the first cost of small reservoirs is usually somewhat
high, but in view of their permanent service and the value of the
water to the dry-farm they pay a very handsome interest on the
investment. It is always a mistake for the dry-farmer to postpone
the construction of a reservoir for the storing of the small
quantities of water that he may possess, in order to save a little
money. Perhaps the greatest objection to the use of the reservoirs
is not their relatively high cost, but the fact that since they
are usually small and the water shallow, too large a proportion of
the water, even under favorable conditions, is lost by
evaporation. It is ordinarily assumed that one half of the water
stored in small reservoirs throughout the year is lost by direct
evaporation.
Available subterranean water
Where surface waters are not readily available, the subterranean
water is of first importance. It is generally known that,
underlying the earth's surface at various depths, there is a large
quantity of free water. Those living in humid climates often
overestimate the amount of water so held in the earth's crust, and
it is probably true that those living in arid regions
underestimate the quantity of water so found. The fact of the
matter seems to be that free water is found everywhere under the
earth's surface. Those familiar with the arid West have frequently
been surprised by the frequency with which water has been found at
comparatively shallow depths in the most desert locations. Various
estimates have been made as to the quantity of underlying water.
The latest calculation and perhaps the most reliable is that made
by Fuller, who, after a careful analysis of the factors involved,
concludes that the total free water held in the earth's crust is
equivalent to a uniform sheet of water over the entire surface of
the earth ninety-six feet in depth. A quantity of water thus held
would be equivalent to about one hundredth part of the whole
volume of the ocean. Even though the thickness of the water sheet
under arid soils is only half this figure there is an amount, if
it could be reached, that would make possible the establishment of
homesteads over the whole dry-farm territory. One of the main
efforts of the day is the determination of the occurrence of the
subterranean waters in the dry-farm territory.
Ordinary dug wells frequently reach water at comparatively shallow
depths. Over the cultivated Utah deserts water is often found at a
depth of twenty-five or thirty feet, though many wells dug to a
depth of one hundred and seventy-five and two hundred feet have
failed to reach water. It may be remarked in this connection that
even where the distance to the water is small, the piped well has
been found to be superior to the dug well. Usually, water is
obtained in the dry-farm territory by driving pipes to
comparatively great depths, ranging from one hundred feet to over
one thousand feet. At such depths water is nearly always found.
Often the geological conditions are such as to force the water up
above the surface as artesian wells, though more often the
pressure is simply sufficient to bring the water within easy
pumping distance of the surface. In connection with this subject
it must be said that many of the subterranean waters of the
dry-farm territory are of a saline character. The amount of
substances held in solution varies largely, but frequently is far
above the limits of safety for the use of man or beast or plants.
The dry-farmer who secures a well of this type should, therefore,
be careful to have a proper examination made of the constituents
of the water before ordinary use is made of it.
Now, as has been said, the utilization of the subterranean waters
of the land is one of the living problems of dry-farming. The
tracing out of this layer of water is very difficult to accomplish
and cannot be done by individuals. It is a work that properly
belongs to the state and national government. The state of Utah,
which was the pioneer in appropriating money for dry-farm
experiments, also led the way in appropriating money for the
securing of water for the dry-farms from subterranean sources. The
world has been progressing in Utah since 1905, and water has been
secured in the most unpromising localities. The most remarkable
instance is perhaps the finding of water at a depth of about five
hundred and fifty feet in the unusually dry Dog Valley located
some fifteen miles west of Nephi.
Pumping water
The use of small quantities of water on the dry-farms carries with
it, in most cases, the use of small pumping plants to store and to
distribute the water properly. Especially, whenever subterranean
sources of water are used and the water pressure is not sufficient
to throw the water above the ground, pumping must be resorted to.
The pumping of water for agricultural purposes is not at all new.
According to Fortier, two hundred thousand acres of land are
irrigated with water pumped from driven wells in the state of
California alone. Seven hundred and fifty thousand acres are
irrigated by pumping in the United States, and Mead states that
there are thirteen million acres of land in India which are
irrigated by water pumped from subterranean sources. The
dry-farmer has a choice among several sources of power for the
operation of his pumping plant. In localities where winds are
frequent and of sufficient strength windmills furnish cheap and
effective power, especially where the lift is not very great. The
gasoline engine is in a state of considerable perfection and may
be used economically where the price of gasoline is reasonable.
Engines using crude oil may be most desirable in the localities
where oil wells have been found. As the manufacture of alcohol
from the waste products of the farms becomes established, the
alcohol-burning engine could become a very important one. Over
nearly the whole of the dry-farm territory coal is found in large
quantities, and the steam engine fed by coal is an important
factor in the pumping of water for irrigation purposes. Further,
in the mountainous part of the dry-farm territory water Power is
very abundant. Only the smallest fraction of it has as yet been
harnessed for the generation of the electric current. As electric
generation increases, it should be comparatively easy for the
farmer to secure sufficient electric power to run the pump. This
has already become an established practice in districts where
electric power is available.
During the last few years considerable work has been done to
determine the feasibility of raising water for irrigation by
pumping. Fortier reports that successful results have been
obtained in Colorado, Wyoming, and Montana. He declares that a
good type of windmill located in a district where the average wind
movement is ten miles per hour can lift enough water twenty feet
to irrigate five acres of land. Wherever the water is near the
surface this should be easy of accomplishment. Vernon, Lovett, and
Scott, who worked under New Mexico conditions, have reported that
crops can be produced profitably by the use of water raised to the
surface for irrigation. Fleming and Stoneking, who conducted very
careful experiments on the subject in New Mexico, found that the
cost of raising through one foot a quantity of water corresponding
to a depth of one foot over one acre of land varied from a cent
and an eighth to nearly twenty-nine cents, with an average of a
little more than ten cents. This means that the cost of raising
enough water to cover one acre to a depth of one foot through a
distance of forty feet would average $4.36. This includes not only
the cost of the fuel and supervision of the pump but the actual
deterioration of the plant. Smith investigated the same problem
under Arizona conditions and found that it cost approximately
seventeen cents to raise one acre foot of water to a height of one
foot. A very elaborate investigation of this nature was conducted
in California by Le Conte and Tait. They studied a large number of
pumping plants in actual operation under California conditions,
and determined that the total cost of raising one acre foot of
water one foot was, for gasoline power, four cents and upward;.
for electric power, seven to sixteen cents, and for steam, four
cents and upward. Mead has reported observations on seventy-two
windmills near Garden City, Kansas, which irrigated from one
fourth to seven acres each at a cost of seventy-five cents to $6
per acre. All in all, these results justify the belief that water
may be raised profitably by pumping for the purpose of irrigating
crops. When the very great value of a little water on a dry-farm
is considered, the figures here given do not seem at all
excessive. It must be remarked again that a reservoir of some sort
is practically indispensable in connection with a pumping plant if
the irrigation water is to be used in the best way.
The use of small quantities of
water in irrigation
Now, it is undoubtedly true that the acre cost of water on
dry-farms, where pumping plants or similar devices must be used
with expensive reservoirs, is much higher than when water is
obtained from gravity canals. It is, therefore, important that the
costly water so obtained be used in the most economical manner.
This is doubly important in view of the fact that the water supply
obtained on dry-farms is always small and insufficient for all
that the farmer would like to do. Indeed, the profit in storing
and pumping water rests largely upon the economical application of
water to crops. This necessitates the statement of one of the
first principles of scientific irrigation practices, namely, that
the yield of a crop under irrigation is not proportional to the
amount of water applied in the form of irrigation water. In other
words, the water stored in the soil by the natural precipitation
and the water that falls during the spring and summer can either
mature a small crop or bring a crop near maturity. A small amount
of water added in the form of irrigation water at the right time
will usually complete the work and produce a well-matured crop of
large yield. Irrigation should only be supplemented to the natural
precipitation. As more irrigation water is added, the increase in
yield becomes smaller in proportion to the amount of water
employed. This is clearly shown by the following table, which is
taken from some of the irrigation experiments carried on at the
Utah Station:--
| Depth of Water Applied (Inches) | Wheat (Bushels) |
Corn (Bushels) |
Alfalfa (Pounds) |
Potatoes (Bushels) |
Sugar Beets (Tons) |
| 5.0 | 40 | 194 | 25 | ||
| 7.5 | 41 | 65 | |||
| 10.0 | 41 | 80 | 213 | 26 | |
| 15.0 | 46 | 78 | 253 | 27 | |
| 25.0 | 49 | 77 | 10,056 | 258 | |
| 35.0 | 55 | 9,142 | 291 | 26 | |
| 50 | 60 | 84 | 13,061 |
THE great nations of antiquity lived and prospered in arid and
semiarid countries. In the more or less rainless regions of China,
Mesopotamia, Palestine, Egypt, Mexico, and Peru, the greatest
cities and the mightiest peoples flourished in ancient days. Of
the great civilizations of history only that of Europe has rooted
in a humid climate. As Hilgard has suggested, history teaches that
a high civilization goes hand in hand with a soil that thirsts for
water. To-day, current events point to the arid and semiarid
regions as the chief dependence of our modern civilization.
In view of these facts it may be inferred that dry-farming is an
ancient practice. It is improbable that intelligent men and women
could live in Mesopotamia, for example, for thousands of years
without discovering methods whereby the fertile soils could be
made to produce crops in a small degree at least without
irrigation. True, the low development of implements for soil
culture makes it fairly certain that dry-farming in those days was
practiced only with infinite labor and patience; and that the
great ancient nations found it much easier to construct great
irrigation systems which would make crops certain with a minimum
of soil tillage, than so thoroughly to till the soil with
imperfect implements as to produce certain yields without
irrigation. Thus is explained the fact that the historians of
antiquity speak at length of the wonderful irrigation systems, but
refer to other forms of agriculture in a most casual manner. While
the absence of agricultural machinery makes it very doubtful
whether dry-farming was practiced extensively in olden days, yet
there can be little doubt of the high antiquity of the practice.
Kearney quotes Tunis as an example of the possible extent of
dry-farming in early historical days. Tunis is under an average
rainfall of about nine inches, and there are no evidences of
irrigation having been practiced there, yet at El Djem are the
ruins of an amphitheater large enough to accommodate sixty
thousand persons, and in an area of one hundred square miles there
were fifteen towns and forty-five villages. The country,
therefore, must have been densely populated. In the seventh
century, according to the Roman records, there were two million
five hundred thousand acres of olive trees growing in Tunis and
cultivated without irrigation. That these stupendous groves
yielded well is indicated by the statement that, under the
Caesar's Tunis was taxed three hundred thousand gallons of olive
oil annually. The production of oil was so great that from one
town it was piped to the nearest shipping port. This historical
fact is borne out by the present revival of olive culture in
Tunis, mentioned in Chapter XII.
Moreover, many of the primitive peoples of to-day, the Chinese,
Hindus, Mexicans, and the American Indians, are cultivating large
areas of land by dry-farm methods, often highly perfected, which
have been developed generations ago, and have been handed down to
the present day. Martin relates that the Tarahumari Indians of
northern Chihuahua, who are among the most thriving aboriginal
tribes of northern Mexico, till the soil by dry-farm methods and
succeed in raising annually large quantities of corn and other
crops. A crop failure among them is very uncommon. The early
American explorers, especially the Catholic fathers, found
occasional tribes in various parts of America cultivating the soil
successfully without irrigation. All this points to the high
antiquity of agriculture without irrigation in arid and semiarid
countries.
Modern dry-farming in the United
States
The honor of having originated modern dry-farming belongs to the
people of Utah. On July 24th, 1847, Brigham Young with his band of
pioneers entered Great Salt Lake Valley, and on that day ground
was plowed, potatoes planted, and a tiny stream of water led from
City Creek to cover this first farm. The early endeavors of the
Utah pioneers were devoted almost wholly to the construction of
irrigation systems. The parched desert ground appeared so
different from the moist soils of Illinois and Iowa, which the
pioneers had cultivated, as to make it seem impossible to produce
crops without irrigation. Still, as time wore on, inquiring minds
considered the possibility of growing crops without irrigation;
and occasionally when a farmer was deprived of his supply of
irrigation water through the breaking of a canal or reservoir it
was noticed by the community that in spite of the intense heat the
plants grew and produced small yields.
Gradually the conviction grew upon the Utah pioneers that farming
without irrigation was not an impossibility; but the small
population were kept so busy with their small irrigated farms that
no serious attempts at dry-farming were made during the first
seven or eight years. The publications of those days indicate that
dry-farming must have been practiced occasionally as early as 1854
or 1855.
About 1863 the first dry-farm experiment of any consequence
occurred in Utah. A number of emigrants of Scandinavian descent
had settled in what is now known as Bear River City, and had
turned upon their farms the alkali water of Malad Creek, and
naturally the crops failed. In desperation the starving settlers
plowed up the sagebrush land, planted grain, and awaited results.
To their surprise, fair yields of grain were obtained, and since
that day dry-farming has been an established practice in that
portion of the Great Salt Lake Valley. A year or two later,
Christopher Layton, a pioneer who helped to build both Utah and
Arizona, plowed up land on the famous Sand Ridge between Salt Lake
City and Ogden and demonstrated that dry-farm wheat could be grown
successfully on the deep sandy soil which the pioneers had held to
be worthless for agricultural purposes. Since that day the Sand
Ridge has been famous as a dry-farm district, and Major J. W.
Powell, who saw the ripened fields of grain in the hot dry sand,
was moved upon to make special mention of them in his volume on
the "Arid Lands of Utah," published in 1879.
About this time, perhaps a year or two later, Joshua Salisbury and
George L. Farrell began dry-farm experiments in the famous Cache
Valley, one hundred miles north of Salt Lake City. After some
years of experimentation, with numerous failures these and other
pioneers established the practice of dry-farming in Cache Valley,
which at present is one of the most famous dry-farm sections in
the United States. In Tooele County, Just south of Salt Lake City,
dry-farming was practiced in 1877--how much earlier is not known.
In the northern Utah counties dry-farming assumed proportions of
consequence only in the later '70's and early '80's. During the
'80's it became a thoroughly established and extensive business
practice in the northern part of the state.
California, which was settled soon after Utah, began dry-farm
experiments a little later than Utah. The available information
indicates that the first farming without irrigation in California
began in the districts of somewhat high precipitation. As the
population increased, the practice was pushed away from the
mountains towards the regions of more limited rainfall. According
to Hilgard, successful dry-farming on an extensive scale has been
practiced in California since about 1868. Olin reports that
moisture-saving methods were used on the Californian farms as
early as 1861. Certainly, California was a close second in
originating dry-farming.
The Columbia Basin was settled by Mareus Whitman near Walla Walla
in 1836, but farming did not gain much headway until the railroad
pushed through the great Northwest about 1880. Those familiar with
the history of the state of Washington declare that dry-farming
was in successful operation in isolated districts in the late
'70's. By 1890 it was a well-established practice, but received a
serious setback by the financial panic of 1892-1893. Really
successful and extensive dry-farming in the Columbia Basin began
about 1897. The practice of summer fallow had begun a year or two
before. It is interesting to note that both in California and
Washington there are districts in which dry-farming has been
practiced successfully under a precipitation of about ten inches
whereas in Utah the limit has been more nearly twelve inches.
In the Great Plains area the history of dry-farming Is hopelessly
lost in the greater history of the development of the eastern and
more humid parts of that section of the country. The great influx
of settlers on the western slope of the Great Plains area occurred
in the early '80's and overflowed into eastern Colorado and
Wyoming a few years later. The settlers of this region brought
with them the methods of humid agriculture and because of the
relatively high precipitation were not forced into the careful
methods of moisture conservation that had been forced upon Utah,
California, and the Columbia Basin. Consequently, more failures in
dry-farming are reported from those early days in the Great Plains
area than from the drier sections of the far West Dry-farming was
practiced very successfully in the Great Plains area during the
later '80's. According to Payne, the crops of 1889 were very good;
in 1890, less so; in 1891, better; in 1892 such immense crops were
raised that the settlers spoke of the section as God's country; in
1893, there was a partial failure, and in 1894 the famous complete
failure, which was followed in 1895 by a partial failure. Since
that time fair crops have been produced annually. The dry years of
1893-1895 drove most of the discouraged settlers back to humid
sections and delayed, by many years, the settlement and
development of the western side of the Great Plains area. That
these failures and discouragements were due almost entirely to
improper methods of soil culture is very evident to the present
day student of dry-farming. In fact, from the very heart of the
section which was abandoned in 1893-1895 come reliable records,
dating back to 1886, which show successful crop production every
year. The famous Indian Head experimental farm of Saskatchewan, at
the north end of the Great Plains area, has an unbroken record of
good crop yields from 1888, and the early '90's were quite as dry
there as farther south. However, in spite of the vicissitudes of
the section, dry-farming has taken a firm hold upon the Great
Plains area and is now a well- established practice.
The curious thing about the development of dry-farming in Utah,
California, Washington, and the Great Plains is that these four
sections appear to have originated dry-farming independently of
each other. True, there was considerable communication from 1849
onward between Utah and California, and there is a possibility
that some of the many Utah settlers who located in California
brought with them accounts of the methods of dry-farming as
practiced in Utah. This, however, cannot be authenticated. It is
very unlikely that the farmers of Washington learned dry-farming
from their California or Utah neighbors, for until 1880
communication between Washington and the colonies in California
and Utah was very difficult, though, of course, there was always
the possibility of accounts of agricultural methods being carried
from place to place by the moving emigrants. It is fairly certain
that the Great Plains area did not draw upon the far West for
dry-farm methods. The climatic conditions are considerably
different and the Great Plains people always considered themselves
as living in a very humid country as compared with the states of
the far West. It may be concluded, therefore, that there were four
independent pioneers in dry-farming in United States. Moreover,
hundreds, probably thousands, of individual farmers over the
semiarid region have practiced dry-farming thirty to fifty years
with methods by themselves.
Although these different dry-farm sections were developed
independently, yet the methods which they have finally adopted are
practically identical and include deep plowing, unless the subsoil
is very lifeless; fall plowing; the planting of fall grain
wherever fall plowing is possible; and clean summer fallowing.
About 1895 the word began to pass from mouth to mouth that
probably nearly all the lands in the great arid and semiarid
sections of the United States could be made to produce profitable
crops without irrigation. At first it was merely a whisper; then
it was talked aloud, and before long became the great topic of
conversation among the thousands who love the West and wish for
its development. Soon it became a National subject of discussion.
Immediately after the close of the nineteenth century the new
awakening had been accomplished and dry-farming was moving onward
to conquer the waste places of the earth.
H. W. Campbell
The history of the new awakening in dry-farming cannot well be
written without a brief account of the work of H. W. Campbell who,
in the public mind, has become intimately identified with the
dry-farm movement. H. W. Campbell came from Vermont to northern
South Dakota in 1879, where in 1882 he harvested a banner
crop,--twelve thousand bushels of wheat from three hundred acres.
In 1883, on the same farm he failed completely. This experience
led him to a study of the conditions under which wheat and other
crops may be produced in the Great Plains area. A natural love for
investigation and a dogged persistence have led him to give his
life to a study of the agricultural problems of the Great Plains
area. He admits that his direct inspiration came from the work of
Jethro Tull, who labored two hundred years ago, and his disciples.
He conceived early the idea that if the soil were packed near the
bottom of the plow furrow, the moisture would be retained better
and greater crop certainty would result. For this purpose the
first subsurface packer was invented in 1885. Later, about 1895,
when his ideas had crystallized into theories, he appeared as the
publisher of Campbell's " Soil Culture and Farm Journal." One page
of each issue was devoted to a succinct statement of the "Campbell
Method." It was in 1898 that the doctrine of summer tillage was
begun to be investigated by him.
In view of the crop failures of the early '90's and the gradual
dry-farm awakening of the later '90's, Campbell's work was
received with much interest. He soon became identified with the
efforts of the railroads to maintain demonstration farms for the
benefit of intending settlers. While Campbell has long been in the
service of the railroads of the semiarid region, yet it should be
said in all fairness that the railroads and Mr. Campbell have had
for their primary object the determination of methods whereby the
farmers could be made sure of successful crops.
Mr. Campbell's doctrines of soil culture, based on his accumulated
experience, are presented in Campbell's "Soil Culture Manual," the
first edition of which appeared about 1904 and the latest edition,
considerably extended, was published in 1907. The 1907 manual is
the latest official word by Mr. Campbell on the principles and
methods of the " Campbell system." The essential features of the
system may be summarized as follows: The storage of water in the
soil is imperative for the production of crops in dry years. This
may be accomplished by proper tillage. Disk the land immediately
after harvest; follow as soon as possible with the plow; follow
the plow with the subsurface packer; and follow the packer with
the smoothing harrow. Disk the land again as early as possible in
the spring and stir the soil deeply and carefully after every
rain. Sow thinly in the fall with a drill. If the grain is too
thick in the spring, harrow it out. To make sure of a crop, the
land should be "summer tilled," which means that clean summer
fallow should be practiced every other year, or as often as may be
necessary.
These methods, with the exception of the subsurface packing, are
sound and in harmony with the experience of the great dry-farm
sections and with the principles that are being developed by
scientific investigation. The "Campbell system" as it stands
to-day is not the system first advocated by him. For instance, in
the beginning of his work he advocated sowing grain in April and
in rows so far apart that spring tooth harrows could be used for
cultivating between the rows. This method, though successful in
conserving moisture, is too expensive and is therefore superseded
by the present methods. Moreover, his farm paper of 1896,
containing a full statement of the "Campbell method," makes
absolutely no mention of "summer tillage," which is now the very
keystone of the system. These and other facts make it evident that
Mr. Campbell has very properly modified his methods to harmonize
with the best experience, but also invalidate the claim that he is
the author of the dry-farm system. A weakness of the "Campbell
system" is the continual insistence upon the use of the subsurface
packer. As has already been shown, subsurface packing is of
questionable value for successful crop production, and if
valuable, the results may be much more easily and successfully
obtained by the use of the disk and harrow and other similar
implements now on the market. Perhaps the one great weakness in
the work of Campbell is that he has not explained the principles
underlying his practices. His publications only hint at the
reasons. H. W. Campbell, however, has done much to popularize the
subject of dry-farming and to prepare the way for others. His
persistence in his work of gathering facts, writing, and speaking
has done much to awaken interest in dry-farming. He has been as "a
voice in the wilderness" who has done much to make possible the
later and more systematic study of dry-farming. High honor should
be shown him for his faith in the semiarid region, for his keen
observation, and his persistence in the face of difficulties. He
is justly entitled to be ranked as one of the great workers in
behalf of the reclamation, without irrigation, of the rainless
sections of the world.
The experiment stations
The brave pioneers who fought the relentless dryness of the Great
American Desert from the memorable entrance of the Mormon pioneers
into the valley of the Great Salt Lake in 1847 were not the only
ones engaged in preparing the way for the present day of great
agricultural endeavor. Other, though perhaps more indirect, forces
were also at work for the future development of the semiarid
section. The Morrill Bill of 1862, making it possible for
agricultural colleges to be created in the various states and
territories, indicated the beginning of a public feeling that
modern methods should be applied to the work of the farm. The
passage in 1887 of the Hatch Act, creating agricultural experiment
stations in all of the states and territories, finally initiated a
new agricultural era in the United States. With the passage of
this bill, stations for the application of modern science to crop
production were for the first time authorized in the regions of
limited rainfall, with the exception of the station connected with
the University of California, where Hilgard from 1872 had been
laboring in the face of great difficulties upon the agricultural
problems of the state of California. During the first few years of
their existence, the stations were busy finding men and problems.
The problems nearest at hand were those that had been attacked by
the older stations founded under an abundant rainfall and which
could not be of vital interest to arid countries. The western
stations soon began to attack their more immediate problems, and
it was not long before the question of producing crops without
irrigation on the great unirrigated stretches of the West was
discussed among the station staffs and plans were projected for a
study of the methods of conquering the desert.
The Colorado Station was the first to declare its good intentions
in the matter of dry-farming, by inaugurating definite
experiments. By the action of the State Legislature of 1893,
during the time of the great drouth, a substation was established
at Cheyenne Wells, near the west border of the state and within
the foothills of the Great Plains area. From the summer of 1894
until 1900 experiments were conducted on this farm. The
experiments were not based upon any definite theory of
reclamation, and consequently the work consisted largely of the
comparison of varieties, when soil treatment was the all-important
problem to be investigated. True in 1898, a trial of the "Campbell
method" was undertaken. By the time this Station had passed its
pioneer period and was ready to enter upon more systematic
investigation, it was closed. Bulletin 59 of the Colorado Station,
published in 1900 by J. E. Payne, gives a summary of observations
made on the Cheyenne Wells substation during seven years. This
bulletin is the first to deal primarily with the experimental work
relating to dry-farming in the Great Plains area. It does not
propose or outline any system of reclamation. Several later
publications of the Colorado Station deal with the problems
peculiar to the Great Plains.
At the Utah Station the possible conquest of the sagebrush deserts
of the Great Basin without irrigation was a topic of common
conversation during the years 1894 and 1895. In 1896 plans were
presented for experiments on the principles of dry-farming. Four
years later these plans were carried into effect. In the summer of
1901, the author and L. A. Merrill investigated carefully the
practices of the dry-farms of the state. On the basis of these
observations and by the use of the established principles of the
relation of water to soils and plants, a theory of dry-farming was
worked out which was published in Bulletin 75 of the Utah Station
in January, 1902. This is probably the first systematic
presentation of the principles of dry-farming. A year later the
Legislature of the state of Utah made provision for the
establishment and maintenance of six experimental dry-farms to
investigate in different parts of the state the possibility of
dry-farming and the principles underlying the art. These stations,
which are still maintained, have done much to stimulate the growth
of dry-farming in Utah. The credit of first undertaking and
maintaining systematic experimental work in behalf of dry-farming
should be assigned to the state of Utah. Since dry-farm
experiments began in Utah in 1901, the subject has been a leading
one in the Station and the College. A large number of men trained
at the Utah Station and College have gone out as investigators of
dry-farming under state and Federal direction.
The other experiment stations in the arid and semi-arid region
were not slow to take up the work for their respective states.
Fortier and Linfield, who had spent a number of years in Utah and
had become somewhat familiar with the dry-farm practices of that
state, initiated dry-farm investigations in Montana, which have
been prosecuted with great vigor since that time. Vernon, under
the direction of Foster, who had spent four years in Utah as
Director of the Utah Station, initiated the work in New Mexico. In
Wyoming the experimental study of dry-farm lands began by the
private enterprise of H. B. Henderson and his associates. Later V.
T. Cooke was placed in charge of the work under state auspices,
and the demonstration of the feasibility of dry-farming in Wyoming
has been going on since about 1907. Idaho has also recently
undertaken dry-farm investigations. Nevada, once looked upon as
the only state in the Union incapable of producing crops without
irrigation, is demonstrating by means of state appropriations that
large areas there are suitable for dry-farming. In Arizona, small
tracts in this sun-baked state are shown to be suitable for
dry-farm lands. The Washington Station is investigating the
problems of dry-farming peculiar to the Columbia Basin, and the
staff of the Oregon Station is carrying on similar work. In
Nebraska, some very important experiments dry-farming are being
conducted. In North Dakota there were in 1910 twenty-one dry-farm
demonstration farms. In South Dakota, Kansas, and Texas,
provisions are similarly made for dry-farm investigations. In
fact, up and down the Great Plains area there are stations
maintained by the state or Federal government for the purpose of
determining the methods under which crops can be produced without
irrigation.
At the head of the Great Plains area at Saskatchewan one of the
oldest dry-farm stations in America is located (since 1888). In
Russia several stations are devoted very largely to the problems
of dry land agriculture. To be especially mentioned for the
excellence of the work done are the stations at Odessa, Cherson,
and Poltava. This last-named Station has been established since
1886.
In connection with the work done by the experiment stations should
be mentioned the assistance given by the railroads. Many of the
railroads owning land along their respective lines are greatly
benefited in the selling of these lands by a knowledge of the
methods whereby the lands may be made productive. However, the
railroads depend chiefly for their success upon the increased
prosperity of the population along their lines and for the purpose
of assisting the settlers in the arid West considerable sums have
been expended by the railroads in cooperation with the stations
for the gathering of information of value in the reclamation of
arid lands without irrigation.
It is through the efforts of the experiment stations that the
knowledge of the day has been reduced to a science of dry-farming.
Every student of the subject admits that much is yet to be learned
before the last word has been said concerning the methods of
dry-farming in reclaiming the waste places of the earth. The
future of dry-farming rests almost wholly upon the energy and
intelligence with which the experiment stations in this and other
countries of the world shall attack the special problems connected
with this branch of agriculture.
The United States Department of
Agriculture
The Commissioner of Agriculture of the United States was given a
secretaryship in the President's Cabinet in 1889. With this added
dignity, new life was given to the department. Under the direction
of J. Sterling Morton preliminary work of great importance was
done. Upon the appointment of James Wilson as Secretary of
Agriculture, the department fairly leaped into a fullness of
organization for the investigation of the agricultural problems of
the country. From the beginning of its new growth the United
States Department of Agriculture has given some thought to the
special problems of the semiarid region, especially that part
within the Great Plains. Little consideration was at first given
to the far West. The first method adopted to assist the farmers of
the plains was to find plants with drouth resistant properties.
For that purpose explorers were sent over the earth, who returned
with great numbers of new plants or varieties of old plants, some
of which, such as the durum wheats, have shown themselves of great
value in American agriculture. The Bureaus of Plant Industry,
Soils, Weather, and Chemistry have all from the first given
considerable attention to the problems of the arid region. The
Weather Bureau, long established and with perfected methods, has
been invaluable in guiding investigators into regions where
experiments could be undertaken with some hope of success. The
Department of Agriculture was somewhat slow, however, in
recognizing dry-farming as a system of agriculture requiring
special investigation. The final recognition of the subject came
with the appointment, in 1905, of Chilcott as expert in charge of
dry-land investigations. At the present time an office of dry-land
investigations has been established under the Bureau of Plant
Industry, which cooperates with a number of other divisions of the
Bureau in the investigation of the conditions and methods of
dry-farming. A large number of stations are maintained by the
Department over the arid and semiarid area for the purpose of
studying special problems, many of which are maintained in
connection with the state experiment stations. Nearly all the
departmental experts engaged in dry-farm investigation have been
drawn from the service of the state stations and in these stations
had received their special training for their work. The United
States Department of Agriculture has chosen to adopt a strong
conservatism in the matter of dry-farming. It may be wise for the
Department, as the official head of the agricultural interests of
the country, to use extreme care in advocating the settlement of a
region in which, in the past, farmers had failed to make a living,
yet this conservatism has tended to hinder the advancement of
dry-farming and has placed the departmental investigations of
dry-farming in point of time behind the pioneer investigations of
the subject.
The Dry-farming Congress
As the great dry-farm wave swept over the country, the need was
felt on the part of experts and laymen of some means whereby
dry-farm ideas from all parts of the country could be exchanged.
Private individuals by the thousands and numerous state and
governmental stations were working separately and seldom had a
chance of comparing notes and discussing problems. A need was felt
for some central dry-farm organization. An attempt to fill this
need was made by the people of Denver, Colorado, when Governor
Jesse F. McDonald of Colorado issued a call for the first
Dry-farming Congress to be held in Denver, January 24, 25, and 26,
1907. These dates were those of the annual stock show which had
become a permanent institution of Denver and, in fact, some of
those who were instrumental in the calling of the Dry-farming
Congress thought that it was a good scheme to bring more people to
the stock show. To the surprise of many the Dry-farming Congress
became the leading feature of the week. Representatives were
present from practically all the states interested in dry-farming
and from some of the humid states. Utah, the pioneer dry-farm
state, was represented by a delegation second in size only to that
of Colorado, where the Congress was held. The call for this
Congress was inspired, in part at least, by real estate men, who
saw in the dry-farm movement an opportunity to relieve themselves
of large areas of cheap land at fairly good prices. The Congress
proved, however, to be a businesslike meeting which took hold of
the questions in earnest, and from the very first made it clear
that the real estate agent was not a welcome member unless he came
with perfectly honest methods.
The second Dry-farming Congress was held January 22 to 25, 1908,
in Salt Lake City, Utah, under the presidency of Fisher Harris. It
was even better attended than the first. The proceedings show that
it was a Congress at which the dry-farm experts of the country
stated their findings. A large exhibit of dry-farm products was
held in connection with this Congress, where ocular demonstrations
of the possibility of dry-farming were given any doubting Thomas.
The third Dry-farming Congress was held February 23 to 25, 1909,
at Cheyenne, Wyoming, under the presidency of Governor W. W.
Brooks of Wyoming. An unusually severe snowstorm preceded the
Congress, which prevented many from attending, yet the number
present exceeded that at any of the preceding Congresses. This
Congress was made notable by the number of foreign delegates who
had been sent by their respective countries to investigate the
methods pursued in America for the reclamation of the arid
districts. Among these delegates were representatives from Canada,
Australia, The Transvaal, Brazil, and Russia.
The fourth Congress was held October 26 to 28, 1909, in Billings,
Montana, under the presidency of Governor Edwin L. Morris of
Montana. The uncertain weather of the winter months had led the
previous Congress to adopt a time in the autumn as the date of the
annual meeting. This Congress became a session at which many of
the principles discussed during the three preceding Congresses
were crystallized into definite statements and agreed upon by
workers from various parts of the country. A number of foreign
representatives were present again. The problems of the Northwest
and Canada were given special attention. The attendance was larger
than at any of the preceding Congresses.
The fifth Congress will be held under the presidency of Hon. F. W.
Mondell of Wyoming at Spokane, Washington, during October, 1910.
It promises to exceed any preceding Congress in attendance and
interest.
The Dry-farming Congress has made itself one of the most important
factors in the development of methods for the reclamation of the
desert. Its published reports are the most valuable publications
dealing with dry-land agriculture. Only simple justice is done
when it is stated that the success of the Dry-farming Congress is
due in a large measure to the untiring and intelligent efforts of
John T. Burns, who is the permanent secretary of the Congress, and
who was a member of the first executive committee.
Nearly all the arid and semiarid states have organized state
dry-farming congresses. The first of these was the Utah
Dry-farming Congress, organized about two months after the first
Congress held in Denver. The president is L. A. Merrill, one of
the pioneer dry-farm investigators of the Rockies.
Jethro Tull (see frontispiece)
A sketch of the history of dry-farming would be incomplete without
a mention of the life and work of Jethro Tull. The agricultural
doctrines of this man, interpreted in the light of modern science,
are those which underlie modern dry-farming. Jethro Tull was born
in Berkshire, England, 1674, and died in 1741. He was a lawyer by
profession, but his health was so poor that he could not practice
his profession and therefore spent most of his life in the
seclusion of a quiet farm. His life work was done in the face of
great physical sufferings. In spite of physical infirmities, he
produced a system of agriculture which, viewed in the light of our
modern knowledge, is little short of marvelous. The chief
inspiration of his system came from a visit paid to south of
France, where he observed "near Frontignan and Setts, Languedoc"
that the vineyards were carefully plowed and tilled in order to
produce the largest crops of the best grapes. Upon the basis of
this observation he instituted experiments upon his own farm and
finally developed his system, which may be summarized as follows:
The amount of seed to be used should be proportional to the
condition of the land, especially to the moisture that is in it.
To make the germination certain, the seed should be sown by drill
methods. Tull, as has already been observed, was the inventor of
the seed drill which is now a feature of all modern agriculture.
Plowing should be done deeply and frequently; two plowings for one
crop would do no injury and frequently would result in an
increased yield. Finally, as the most important principle of the
system, the soil should be cultivated continually, the argument
being that by continuous cultivation the fertility of the soil
would be increased, the water would be conserved, and as the soil
became more fertile less water would be used. To accomplish such
cultivation, all crops should be placed in rows rather far apart,
so far indeed that a horse carrying a cultivator could walk
between them. The horse-hoeing idea of the system became
fundamental and gave the name to his famous book, "The Horse
Hoeing Husbandry," by Jethro Tull, published in parts from 1731 to
1741. Tull held that the soil between the rows was essentially
being fallowed and that the next year the seed could be planted
between the rows of the preceding year and in that way the
fertility could be maintained almost indefinitely. If this method
were not followed, half of the soil could lie fallow every other
year and be subjected to continuous cultivation. Weeds consume
water and fertility and, therefore, fallowing and all the culture
must be perfectly clean. To maintain fertility a rotation of crops
should be practiced. Wheat should be the main grain crop; turnips
the root crop; and alfalfa a very desirable crop.
It may be observed that these teachings are sound and in harmony
with the best knowledge of to-day and that they are the very
practices which are now being advocated in all dry-farm sections.
This is doubly curious because Tull lived in a humid country.
However, it may be mentioned that his farm consisted of a very
poor chalk soil, so that the conditions under which he labored
were more nearly those of an arid country than could ordinarily be
found in a country of abundant rainfall. While the practices of
Jethro Tull were in themselves very good and in general can be
adopted to-day, yet his interpretation of the principles involved
was wrong. In view of the limited knowledge of his day, this was
only to be expected. For instance, he believed so thoroughly in
the value of cultivation of the soil, that he thought it would
take the place of all other methods of maintaining soil-fertility.
In fact, he declared distinctly that "tillage is manure," which we
are very certain at this time is fallacious. Jethro Tull is one of
the great investigators of the world. In recognition of the fact
that, though living two hundred years ago in a humid country, he
was able to develop the fundamental practices of soil culture now
used in dry-farming, the honor has been done his memory of placing
his portrait as the frontispiece of this volume.
CHAPTER XVIII
IT is difficult to obtain a correct view of the present status of
dry-farming, first, because dry-farm surveys are only beginning to
be made and, secondly, because the area under dry-farm cultivation
is increasing daily by leaps and bounds. All arid and semiarid
parts of the world are reaching out after methods of soil culture
whereby profitable crops may be produced without irrigation, and
the practice of dry-farming, according to modern methods, is now
followed in many diverse countries. The United States undoubtedly
leads at present in the area actually under dry-farming, but, in
view of the immense dry-farm districts in other parts of the
world, it is doubtful if the United States will always maintain
its supremacy in dry-farm acreage. The leadership in the
development of a science of dry-farming will probably remain with
the United States for years, since the numerous experiment
stations established for the study of the problems of farming
without irrigation have their work well under way, while, with the
exception of one or two stations in Russia and Canada, no other
countries have experiment stations for the study of dry-farming in
full operation. The reports of the Dry-farming Congress furnish
practically the only general information as to the status of
dry-farming in the states and territories of the United States and
in the countries of the world.
California
In the state of California dry-farming has been
firmly established for more than a generation. The chief crop of
the California dry-farms is wheat, though the other grains, root
crops, and vegetables are also grown without irrigation under a
comparatively small rainfall. The chief dry-farm areas are found
in the Sacramento and the San Joaquin valleys. In the Sacramento
Valley the precipitation is fairly large, but in the San Joaquin
Valley it is very small. Some of the most successful dry-farms of
California have produced well for a long succession of years under
a rainfall of ten inches and less. California offers a splendid
example of the great danger that besets all dry-farm sections. For
a generation wheat has been produced on the fertile Californian
soils without manuring of any kind. As a consequence, the
fertility of the soils has been so far depleted that at present it
is difficult to obtain paying crops without irrigation on soils
that formerly yielded bountifully. The living problem of the
dry-farms in California is the restoration of the fertility which
has been removed from the soils by unwise cropping. All other
dry-farm districts should take to heart this lesson, for, though
crops may be produced on fertile soils for one, two, or even three
generations without manuring, yet the time will come when
plant-food must be added to the soil in return for that which has
been removed by the crops. Meanwhile, California offers, also, an
excellent example of the possibility of successful dry-farming
through long periods and under varying climatic conditions. In the
Golden State dry-farming is a fully established practice; it has
long since passed the experimental stage.
Columbia River Basin
The Columbia River Basin includes the state of Washington, most of
Oregon, the northern and central part of Idaho, western Montana,
and extends into British Columbia. It includes the section often
called the Inland Empire, which alone covers some one hundred and
fifty thousand square miles. The chief dry-farm crop of this
region is wheat; in fact, western Washington or the "Palouse
country" is famous for its wheat-producing powers. The other
grains, potatoes, roots, and vegetables are also grown without
irrigation. In the parts of this dry-farm district where the
rainfall is the highest, fruits of many kinds and of a high
quality are grown without irrigation. It is estimated that at
least two million acres are being dry-farmed in this district.
Dry-farming is fully established in the Columbia River Basin. One
farmer is reported to have raised in one year on his own farm two
hundred and fifty thousand bushels of wheat. In one section of the
district where the rainfall for the last few years has been only
about ten or eleven inches, wheat has been produced successfully.
This corroborates the experience of California, that wheat may
really be grown in localities where the annual rainfall is not
above ten inches. The most modern methods of dry-farming are
followed by the farmers of the Columbia River Basin, but little
attention has been given to soil-fertility, since soils that have
been farmed for a generation still appear to retain their high
productive powers. Undoubtedly, however, in this district, as in
California, the question of soil-fertility will be an important
one in the near future. This is one of the great dry-farm
districts of the world.
The Great Basin
The Great Basin includes Nevada, the western half of Utah, a small
part of southern Oregon and Idaho, and also a part of Southern
California. It is a great interior basin with all its rivers
draining into salt lakes or dry sinks. In recent geological times
the Great Basin was filled with water, forming the great Lake
Bonneville which drained into the Columbia River. In fact, the
Great Basin is made up of a series of great valleys, with very
level floors, representing the old lake bottom. On the bench lands
are seen, in many places, the effects of the wave action of the
ancient lake. The chief dry-farm crop of this district is wheat,
but the other grains, including corn, are also produced
successfully. Other crops have been tried with fair success, but
not on a commercial scale. Grapevines have been made to grow quite
successfully without irrigation on the bench lands. Several small
orchards bearing luscious fruit are growing on the deep soils of
the Great Basin without the artificial application of water.
Though the first dry-farming by modern peoples was probably
practiced in the Great Basin, yet the area at present under
cultivation is not large, possibly a little more than four hundred
thousand acres.
Dry-farming, however, is well established. There
are large areas, especially in Nevada, that receive less than ten
inches of rainfall annually, and one of the leading problems
before the dry-farmers of this district is the determination of
the possibility of producing crops upon such lands without
irrigation. On the older dry-farms, which have existed in some
cases from forty to fifty years, there are no signs of diminution
of soil-fertility. Undoubtedly, however, even under the conditions
of extremely high fertility prevailing in the Great Basin, the
time will soon come when the dry-farmer must make provision for
restoring to the soil some of the fertility taken away by crops.
There are millions of acres in the Great Basin yet to be taken up
and subjected to the will of the dry-farmer.
Colorado and Rio Grande River
Basins
The Colorado and Rio Grande River Basins include Arizona and the
western part of New Mexico. The chief dry-farm crops of this dry
district are wheat, corn, and beans. Other crops have also been
grown in small quantities and with some success. The area suitable
for dry-farming in this district has not yet been fully determined
and, therefore, the Arizona and New Mexico stations are
undertaking dry-farm surveys of their respective states. In spite
of the fact that Arizona is generally looked upon as one of the
driest states of the Union, dry-farming is making considerable
headway there. In New Mexico, five sixths of all the homestead
applications during the last year were for dry-farm lands; and, in
fact, there are several prosperous communities in New Mexico which
are subsisting almost wholly on dry-farming. It is only fair to
say, however, that dry-farming is not yet well established in this
district, but that the prospects are that the application of
scientific principles will soon make it possible to produce
profitable crops without irrigation in large parts of the Colorado
and Rio Grande River Basins.
The Mountain States
This district includes a part of Montana, nearly the whole of
Wyoming and Colorado, and part of eastern Idaho. It is located
along the backbone of the Rocky Mountains. The farms are located
chiefly in valleys and on large rolling table-lands. The chief
dry-farm crop is wheat, though the other crops which are grown
elsewhere on dry-farms may be grown here also. In Montana there is
a very large area of land which has been demonstrated to be well
adapted for dry-farm purposes. In Wyoming, especially on the
eastern as well as on the far western side, dry-farming has been
shown to be successful, but the area covered at the present time
is comparatively small. In Idaho, dry-farming is fairly well
established. In Colorado, likewise, the practice is very well
established and the area is tolerably large. All in all,
throughout the mountain states dry-farming may be said to be well
established, though there is a great opportunity for the extension
of the practice. The sparse population of the western states
naturally makes it impossible for more than a small fraction of
the land to be properly cultivated.
The Great Plains Area
This area includes parts of Montana, North Dakota, South Dakota,
Nebraska, Kansas, Wyoming, Colorado, New Mexico, Oklahoma, and
Texas. It is the largest area of dry-farm land under approximately
uniform conditions. Its drainage is into the Mississippi, and it
covers an area of not less than four hundred thousand square
miles. Dry-farm crops grow well over the whole area; in fact,
dry-farming is well established in this district. In spite of the
failures so widely advertised during the dry season of 1894, the
farmers who remained on their farms and since that time have
employed modern methods have secured wealth from their labors. The
important question before the farmers of this district is that of
methods for securing the best results. From the Dakotas to Texas
the farmers bear the testimony that wherever the soil has been
treated right, according to approved methods, there have been no
crop failures.
Canada
Dry-farming has been pushed vigorously in the semiarid portions of
Canada, and with great success. Dry-farming is now reclaiming
large areas of formerly worthless land, especially in Alberta,
Saskatchewan, and the adjoining provinces. Dry-farming is
comparatively recent in Canada, yet here and there are semiarid
localities where crops have been raised without irrigation for
upwards of a quarter of a century. In Alberta and other places it
has been now practiced successfully for eight or ten years, and it
may be said that dry-farming is a well-established practice in the
semiarid regions of the Dominion of Canada.
Mexico
In Mexico, likewise, dry-farming has been tried and found to be
successful. The natives of Mexico have practiced farming without
irrigation for centuries--and modern methods are now being applied
in the zone midway between the extremely dry and the extremely
humid portions. The irregular distribution of the precipitation,
the late spring and early fall frosts, and the fierce winds
combine to make the dry-farm problem somewhat difficult, yet the
prospects are that, with government assistance, dry-farming in the
near future will become an established practice in Mexico. In the
opinion of the best students of Mexico it is the only method of
agriculture that can be made to reclaim a very large portion of
the country.
Brazil
Brazil, which is greater in area than the United States, also has
a large arid and semiarid territory which can be reclaimed only by
dry-farm methods. Through the activity of leading citizens
experiments in behalf of the dry-farm movement have already been
ordered. The dry-farm district of Brazil receives an annual
precipitation of about twenty-five inches, but irregularly
distributed and under a tropical sun. In the opinion of those who
are familiar with the conditions the methods of dry-farming may be
so adapted as to make dry-farming successful in Brazil.
Australia
Australia, larger than the continental United States, is vitally
interested in dry-farming, for one third of its vast area is under
a rainfall of less than ten inches, and another third is under a
rainfall of between ten and twenty inches. Two thirds of the area
of Australia, if reclaimed at all, must be reclaimed by
dry-farming. The realization of this condition has led several
Australians to visit the United States for the purpose of learning
the methods employed in dry-farming. The reports on dry-farming in
America by Surveyor-General Strawbridge and Senator J. H. McColl
have done much to initiate a vigorous propaganda in behalf of
dry-farming in Australia. Investigation has shown that occasional
farmers are found in Australia, as in America, who have discovered
for themselves many of the methods of dry-farming and have
succeeded in producing crops profitably. Undoubtedly, in time,
Australia will be one of the great dry-farming countries of the
world.
Africa
Up to the present, South Africa only has taken an active interest
in the dry-farm movement, due to the enthusiastic labors of Dr.
William Macdonald of the Transvaal. The Transvaal has an average
annual precipitation of twenty-three inches, with a large district
that receives between thirteen and twenty inches. The rain comes
in the summer, making the conditions similar to those of the Great
Plains. The success of dry-farming has already been practically
demonstrated. The question before the Transvaal farmers is the
determination of the best application of water conserving methods
under the prevailing conditions. Under proper leadership the
Transvaal and other portions of Africa will probably join the
ranks of the larger dry-farming countries of the world.
Russia
More than one fourth of the whole of Russia is so dry as to be
reclaimable only by dry-farming. The arid area of southern
European Russia has a climate very much like that of the Great
Plains. Turkestan and middle Asiatic Russia have a climate more
like that of the Great Basin. In a great number of localities in
both European and Asiatic Russia dry-farming has been practiced
for a number of years. The methods employed have not been of the
most refined kind, due, possibly, to the condition of the people
constituting the farming class. The government is now becoming
interested in the matter and there is no doubt that dry-farming
will also be practiced on a very large scale in Russia.
Turkey
Turkey has also a large area of arid land and, due to American
assistance, experiments in dry-farming are being carried on in
various parts of the country. It is interesting to learn that the
experiments there, up to date, have been eminently successful and
that the prospects now are that modern dry-farming will soon be
conducted on a large scale in the Ottoman Empire.
Palestine
The whole of Palestine is essentially arid and semi-arid and
dry-farming there has been practiced for centuries. With the
application of modern methods it should be more successful than
ever before. Dr. Aaronsohn states that the original wild wheat
from which the present varieties of wheat have descended has been
discovered to be a native of Palestine.
China
China is also interested in dry-farming. The climate of the drier
portions of China is much like that of the Dakotas. Dry-farming
there is of high antiquity, though, of course, the methods are not
those that have been developed in recent years. Under the
influence of the more modern methods dry-farming should spread
extensively throughout China and become a great source of profit
to the empire. The results of dry-farming in China are among the
best.
These countries have been mentioned simply
because they have been represented at the recent Dry-farming
Congresses. Nearly all of the great countries of the world having
extensive semiarid areas are directly interested in dry-farming.
The map on pages 30 and 31 shows that more than 55 per cent of the
world's surface receives an annual rainfall of less than twenty
inches. Dry-farming is a world problem and as such is being
received by the nations.
THE Shadow of the Year of Drouth still obscures the hope of many a
dry-farme From the magazine page and the public platform the
prophet of evil, thinking himself a friend of humanity, solemnly
warns against the arid region and dry-farming, for the year of
drouth, he says, is sure to come again and then will be repeated
the disasters of 1893-1895. Beware of the year of drouth. Even
successful dry-farmers who have obtained good crops every year for
a generation or more are half led to expect a dry year or one so
dry that crops will fail in spite of all human effort. The
question is continually asked, "Can crop yields reasonably be
expected every year, through a succession of dry years, under
"semiarid conditions, if the best methods of dry-farming be
practiced?" In answering this question, it may be said at the very
beginning, that when the year of drouth is mentioned in connection
with dry-farming, sad reference is always made to the experience
on the Great Plains in the early years of the '90's. Now the fact
of the matter is, that while the years of 1893,1894, and 1895 were
dry years, the only complete failure came in 1894. In spite of the
improper methods practiced by the settlers, the willing soil
failed to yield a crop only one year. Moreover, it should not be
forgotten that hundreds of farmers in the driest section during
this dry period, who instinctively or otherwise farmed more nearly
right, obtained good crops even in 1894. The simple practice of
summer fallowing, had it been practiced the year before, would
have insured satisfactory crops in the driest year. Further, the
settlers who did not take to their heels upon the arrival of the
dry year are still living in large numbers on their homesteads and
in numerous instances have accumulated comfortable fortunes from
the land which has been held up so long as a warning against
settlement beyond a humid climate. The failure of 1894 was due as
much to a lack of proper agricultural information and practice as
to the occurrence of a dry year.
Next, the statement is carelessly made that the
recent success in dry-farming is due to the fact that we are now
living in a cycle of wet years, but that as soon as the cycle of
dry years strikes the country dry-farming will vanish as a dismal
failure. Then, again, the theory is proposed that the climate is
permanently changing toward wetness or dryness and the past has no
meaning in reading the riddle of the future. It is doubtless true
that no man may safely predict the weather for future generations;
yet, so far as human knowledge goes, there is no perceptible
average change in the climate from period to period within
historical time; neither are there protracted dry periods followed
by protracted wet periods. The fact is, dry and wet years
alternate. A succession of somewhat wet years may alternate with a
succession of somewhat dry years, but the average precipitation
from decade to decade is very nearly the same. True, there will
always be a dry year, that is, the driest year of a series of
years, and this is the supposedly fearful and fateful year of
drouth. The business of the dry-farmer is always to farm so as to
be prepared for this driest year whenever it comes. If this be
done, the farmer will always have a crop: in the wet years his
crop will be large; in the driest year it will be sufficient to
sustain him.
So persistent is the half-expressed fear that this driest year
makes it impossible to rely upon dry-farming as a permanent system
of agriculture that a search has been made for reliable long
records of the production of crops in arid and semiarid regions.
Public statements have been made by many perfectly reliable men to
the effect that crops have been produced in diverse sections over
long periods of years, some as long as thirty-five or forty
year's, without one failure having occurred. Most of these
statements, however, have been general in their nature and not
accompanied by the exact yields from year to year. Only three
satisfactory records have been found in a somewhat careful search.
Others no doubt exist.
The first record was made by Senator J. G. M.
Barnes of Kaysville, Utah. Kaysville is located in the Great Salt
Lake Valley, about fifteen miles north of Salt Lake City. The
climate is semiarid; the precipitation comes mainly in the winter
and early spring; the summers are dry, and the evaporation is
large. Senator Barnes purchased ninety acres of land in the spring
of 1887 and had it farmed under his own supervision until 1906. He
is engaged in commercial enterprises and did not, himself, do any
of the work on the farm, but employed men to do the necessary
labor. However, he kept a close supervision of the farm and
decided upon the practices which should be followed. From
seventy-eight to eighty-nine acres were harvested for each crop,
with the exception of 1902, when all but about twenty acres was
fired by sparks from the passing railroad train. The plowing,
harrowing, and weeding were done very carefully. The complete
record of the Barnes dry-farm from 1887 to 1905 is shown in the
table on the following page.
|
|
Rainfall (Inches) |
per Acre (Bu.) |
Plowed |
|
| 1887 | 11.66 | -- | May | Sept. |
| 1888 | 13.62 | Failure | May | Sept. |
| 1889 | 18.46 | 22.5 | -- | Volunteer* |
| 1890 | 10.38 | 15.5 | -- | -- |
| 1891 | 15.92 | Fallow | May | Fall |
| 1892 | 14.08 | 19.3 | -- | -- |
|---|---|---|---|---|
| 1893 | 17.35 | Fallow | May | Fall |
| 1894 | 15.27 | 26.0 | -- | -- |
| 1895 | 11.95 | Fallow | May | Aug. |
| 1896 | 18.42 | 22.0 | -- | -- |
| 1897 | 16.74 | Fallow | Spring | Fall |
| 1898 | 16.09 | 26.0 | -- | -- |
| 1899 | 17.57 | Fallow | May | Fall |
| 1900 | 11.53 | 23.5 | -- | -- |
| 1901 | 16.08 | Fallow | Spring | Fall |
| 1902 | 11.41 | 28.9 | Sept. | Fall |
| 1903 | 14.62 | 12.5 | -- | -- |
| 1904 | 16.31 | Fallow | Spring | Fall |
| 1905 | 14.23 | 25.8 | -- | -- |
| Year | Annual Rainfall (Inches)* |
Bushels of Wheat per Acre
Experimental Farm-- Fallow |
Bushels of Wheat per Acre
Experimental Farm-- Stubble |
Bushels of Wheat per Acre Motherwell's Farm |
| 1891 | 14.03 | 35 | 32 | 30 |
| 1892 | 6.92 | 28 | 21 | 28 |
| 1893 | 10.11 | 35 | 22 | 34 |
| 1894 | 3.90 | 17 | 9 | 24 |
| 1895 | 12.28 | 41 | 22 | 26 |
| 1896 | 10.59 | 39 | 29 | 31 |
| 1897 | 14.62 | 33 | 26 | 35 |
| 1898 | 18.03 | 32 | -- | 27 |
| 1899 | 9.44 | 33 | -- | 33 |
| 1900 | 11.74 | 17 | 5 | 25 |
| 1901 | 20.22 | 49 | 38 | 51 |
| 1902 | 10.73 | 38 | 22 | 28 |
| 1903 | 15.55 | 35 | 15 | 31 |
| 1904 | 11.96 | 40 | 29 | 35 |
| 1905 | 19.17 | 42 | 18 | 36 |
| 1906 | 13.21 | 26 | 13 | 38 |
| 1907 | 15.03 | 18 | 18 | 15 |
| 1908 | 13.17 | 29 | 14 | 16 |
| 1909 | 13.96 | 28 | 15 | 23 |
LOCATE the dry-farm in a section with an annual precipitation of
more than ten inches and, if possible, with small wind movement.
One man with four horses and plenty of machinery cannot handle
more than from 160 to 200 acres. Farm fewer acres and farm them
better.
Select a clay loam soil. Other soils may be equally productive,
but are cultivated properly with somewhat more difficulty.
Make sure, with the help of the soil auger, that the soil is of
uniform structure to a depth of at least eight feet. If streaks of
loose gravel or layers of hardpan are near the surface, water may
be lost to the plant roots.
After the land has been cleared and broken let it lie fallow with
clean cultivation, for one year. The increase in the first and
later crops will pay for the waiting.
Always plow the land early in the fall, unless abundant experience
shows that fall plowing is an unwise practice in the locality.
Always plow deeply unless the subsoil is infertile, in which case
plow a little deeper each year until eight or ten inches are
reached Plow at least once for each crop. Spring plowing; if
practiced, should be done as early as possible in the season.
Follow the plow, whether in the fall or spring, with the disk and
that with the smoothing harrow, if crops are to be sown soon
afterward. If the land plowed in the fall is to lie fallow for the
winter, leave it in the rough condition, except in localities
where there is little or no snow and the winter temperature is
high.
Always disk the land in early spring, to prevent evaporation.
Follow the disk with the harrow. Harrow, or in some other way stir
the surface of the soil after every rain. If crops are on the
land, harrow as long as the plants will stand it. If hoed crops,
like corn or potatoes, are grown, use the cultivator throughout
the season. A deep mulch or dry soil should cover the land as far
as possible throughout the summer. Immediately after harvest disk
the soil thoroughly.
Destroy weeds as soon as they show themselves. A weedy dry-farm is
doomed to failure.
Give the land an occasional rest, that is, a clean summer fallow.
Under a rainfall of less than fifteen inches, the land should be
summer fallowed every other year; under an annual rainfall of
fifteen to twenty inches, the summer fallow should occur every
third or fourth year. Where the rainfall comes chiefly in the
summer, the summer fallow is less important in ordinary years than
where the summers are dry and the winters wet. Only an absolutely
clean fallow should be permitted.
The fertility of dry-farm soils must be maintained. Return the
manure; plow under green leguminous crops occasionally and
practice rotation. On fertile soils plants mature with the least
water.
Sow only by the drill method. Wherever possible use fall varieties
of crops. Plant deeply--three or four inches for grain. Plant
early in the fall, especially if the land has been summer
fallowed. Use only about one half as much seed as is recommended
for humid-farming.
All the ordinary crops may be grown by dry-farming. Secure seed
that has been raised on dry-farms. Look out for new varieties,
especially adapted for dry-farming, that may be brought in. Wheat
is king in dry-farming; corn a close second. Turkey wheat promises
the best.
Stock the dry-farm with the best modern machinery. Dry-farming is
possible only because of the modern plow, the disk, the drill
seeder, the harvester, the header, and the thresher.
Make a home on the dry-farm. Store the flood waters in a
reservoir; or pump the underground waters, for irrigating the
family garden. Set out trees, plant flowers, and keep some live
stock.
Learn to understand the reasons back of the principles of
dry-farming, apply the knowledge vigorously, and the crop cannot
fail.
Always farm as if a year of drouth were coming.
Man, by his intelligence, compels the laws of nature to do his
bidding, and thus he achieves joy.
"And God blessed them--and God said unto them, Be fruitful and
multiply and replenish the earth, and subdue it."