American Falls press. [volume] (American Falls, Idaho) 1907-1937, 1911-03-11
Time OF IRRIGATION
Character of Soil and SubsoiI
Has Much Influence.
Sufficient Water Should Be Applied to
Saturate Land to Depth Of Four
to Six Feet-lrrigatIon Should
Be Followed by Harrow.

(By WALTER w. M'LAUGHLIN, Irri-
cation Engineer, Department Of Agri-
c%ulture).
The character of the soil and sub
soil has a large influence upon the
time of i%rrigating. A heavy soil with
tight subsoil will receive large quaint
ties of moisture and hold 1t for a long
time, making 1t possible to irrigate
heavily and at long intervals. If such
a soil is underlaid with gravel the
water will drain out and more fire.
quent irrigation will be necessary.
The same principle holds with lighter
soils. The lighter the soils and the
more open the subsoils the more fire.
quently it will be necessary to irri-
cato. The lighter soils have less wa
ter capacity, so that the irrigations
should be light and frequent.
The ideal condition seems to be to
have sufic moisture in the soil at
the time of seeding to terminate the
seed and keep the plants growing I'M
til they are large enough to shade the
ground when the crop is irrigated. 1t
is irrigated again when the grain is in
the boot-that is, when the heads are
Just beginning to show-and some
times again when the heads are fill
ing.
In localities having a small water
precipitation or where the evapora-
ton is excessive during the winter
months, as is the case along part OF
fho Daa{Go oOoct IN NrnU Mnyi6n Ari-
iona, and a few other localities, the
utility of irrigation during the non
growing season has been demonstrate
ed. Where the water supply is defci-
ent, irrigation at a time when the wa
ter can be obtained, either in the win
ter or the spring before planting, is
of service to store moisture in the soil
for the plants use later in the sea
son. Winter irrigation is not well UNI
derstood or it's benefits realized as
would be the case were the pactice
more extensive. Irrigation prior to
planting is of great service In locali-
ties with a limited water supply
where such supply is required by 9TH
er and more profitable crops later in
the season.
In winter irrigation the land is irrt-
gated once or twice before heavy
freezing weather, the first irrigation
two weeks to a month prior to the
last one, which should occur just be-
for heavy frost. The better method
of winter ~irrigating is by the furrow
method, unless the land can be har-
rowed after the last irrigation, as a
mulched surface during the winter Is
desired, that the winter precipitation
may enter the soil readily. Sufficient
water should be applied to s%aturate
the soil to a depth of four to six feet,
provided the soil is rather deep and
not underlaid neal the surface with
porous material such as sand and
gravel. Some difficulty is experienced
upon the heavy lands In irrigating in
the spring prior to planting, as the
soil dries out very slowly and the
grain cannot be planted until late.
Better results are obtained in such
cases by watering just after the crop
has been planted. The furrow meth
cd is to be preferred upon medium to
heavy coils ii irrigation IS Iequlie
at any time before the plants have at
tanned suffi cient growth to shade the
ground. In case water is applied in
the spring before planting, the land
should be plowed, narrowed, furrowed
and irrigated. The irrigation should
be followed rs soon as possible by
the disk harrow and the float, then by
seeding. If the land has been plow-
ed the previous fall, the disk harrow
should take the place of the pillow.
Furrowing should follow planting for
the purpose of subsequent irrigations-
If the land is not to be irrigated un
til after the grain is planted, the land
should be plowed; if not plowed the
fall previous, double disked, narrow
ed, foated, planted, and ~furrowed, in
the order named. In case the ground
is cloddy. the roller may be used eth
err before or after the disk.
Late summer or early fall irrigation
is proving very satisfactory for de-
stroying weeds upon foul land.