American Falls press. [volume] (American Falls, Idaho) 1907-1937, 1911-03-25

requires from 800 to 5000 pounds
OF water. In climates where the
fal' Is rather high about 400 pounds
are normally required for the pro-
duction of one pound OF dry matter,
while hot. dry climates require an
average of about $50 pounds. On
this basis the production of one
bushel of wheat requires approx
mateIy 81 tons of water and one
ton OF lucern hay not far from $50
tors. or 1900, 900 pounds Of water.
At first thought It would seer that
II such immense quantities of water
are required for plant production.
paying crops with the small annual
precipitation of dry farm countries.
However. a simple calculation will
show that an annual rainfall of IL
inches, II properly stored. In the soil,
is capable of producing about 81
bushels of wheat annually. But the
water to be of value to plants must
be stored In the soil.
The available water In the soil is
the critical factor in dry farming.
With an abundance of soil water
large crops will be depended upon;
as the quantity Of soil water d.
minishes the crop yield likewise d.
mInishes. The most important
practices In the system of dry farm
ms are those that concern them
selves with the storing OF water in
the soil. Deep and fall blowing and
the maintenance OF In absOrptive
soil mulch. which permits the en-
trance OF water into the soil, are
essential in rotation system OF farm
ing without irrigation in countries
of limited rainfall. 1t is not my
purpose. however, to discuss here
the methods whereby water may be
stored in the soil. 1t is rather to
show how the water which has once
been stored in the soil may be used
most economically for plant pro-
duction. Water that has entered tn
soil may be lost In three ways. First
1t may escape by downward seep-
age, passing beyond the reach of
plant roots and often reaching the
standing water. In dry farming dis
tricts such loss Is q rare occurrence
for the natural precipitation Is not
sufficiently large to connect with
the country drainage. and 1t may
therefore be eliminated from consid-
oil alton. Second, soil water may be
lost by direct evaporation from the
surface soil. The conditions pre-
vailing In arid districts favor strong
ly this n of loss of soil mois-
ture. 1t has been shown, however,
by long experience that the farmer,
BY proper and persistent cultiva.
ton Of the top soil q reduce this
loss until 1t Ia almost negligible
Third. soil water may be lost by
evaporation from the plants them
solves through the leaves. While
II " not generally understood, this
source of loss Is. In districts where
dry farming is properly carried on,
very much larger than from seep-
ags or direct evaporation. So long
81 plants are growing evaporation
from plant leaves, ordinarily called
Transportation, continues. Experiment
performed in various arid districts
have shown that one and one-hali
t. three times more water evapOrate
from the plant than directly from IL
we'll Tiled soil. To the present very
little has been learned concerning
the most effective methods Of check.
lug or controlling this continue
loss OF water. Transportation, OF
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.
The oots are organs of water alb
sorption. Practically no water is
taken into the plants by the stems
or leaves, even under conditions of
the real consequence in the water
absorption of plants. The root
systems of plants are very large in
deed. The roots in one acre of an
average wheat crop weigh in the
neighborhood of 1000 pounds. pos
sibly more. These roots are dlstri-
buted to great depths. as has been
recently determined. The roots OF
all the ordinary agricultural crops,
especially those grown under dry
farming conditions. penetrate the
, soil to a depth of from 6 to 10 or
IL feet. Even in humid countries
the distribution OF plant roots Is not
| far from four to six feet. Some
plants, such as lucern and others,
penetrate the soil to much greater
depths-from 80 to so feet-and
many native plants grow on arid
soils to equal depths. The roots Of
these plants are distributed very
thoroughly throughout the soil. so
thai countless numbers Of soil par
ticticles are touched by them. In
one of the famous German investiga-
tions 1t was found that the total
length OF the roots of u wheat
plant was 800 feet and of n rye
plant over 400 feet. King found in
one of his Wisconsin experiments
that the total length OF the roots OF
one corn plant. In the upper three
feet measured 1452 feet, All parts
Of the roots do not possess equal
power OF taking up soil water. In
the process Of water absorption the
young roots are most active and ef-
f~ective. Even in young roots. how
ever. only certain parts are actively
engaged in water absorption. At