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
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
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.