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.