Dry Farming

Pages:
1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18

Edited by Charles Aldarondo (aldarondo@yahoo.com).

DRY-FARMING

A SYSTEM OF AGRICULTURE FOR COUNTRIES UNDER LOW RAINFALL

BY JOHN A. WIDTSOE, A.M., Ph. D

PRESIDENT OF THE AGRICULTURAL COLLEGE OF UTAH

NEW YORK

1920

TO

LEAH

THIS BOOK IS INSCRIBED

JUNE 1, 1910

PREFACE

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.

CHAPTER I

INTRODUCTION

DRY-FARMING DEFINED

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.

CHAPTER II

THE THEORETICAL BASIS OF DRY-FARMING

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:

Pounds Of Water For One Pound Of Dry Matter

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

It is clear from the above results, obtained in Germany, that the
amount of water required to produce a pound of dry matter is not the
same for all plants, nor is it the same under all conditions for the
same plant. In fact, as will be shown in a later chapter, the water
requirements of any crop depend upon numerous factors, more or less
controllable. The range of the above German results is from 233 to
774 pounds, with an average of about 419 pounds of water for each
pound of dry matter produced.

During the late eighties and early nineties, King conducted
experiments similar to the earlier German experiments, to determine
the water requirements of crops under Wisconsin conditions. A
summary of the results of these extensive and carefully conducted
experiments is as follows:--

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.

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?"

CHAPTER III

DRY-FARM AREAS--RAINFALL

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

Pages:
1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18