Dry-Farming | Page 5

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