The Powder River County examiner and the Broadus independent. [volume] (Broadus, Mont.) 1919-1935, 1922-07-28

now uuQTOOuCt1Ve anu Olteu dUauUOu-
ed.
The water-logging Of the soil is the
direct result of seepage from the irri-
cation Of the lands themselves:
seepage from lateral bitches. and to
a small extent seepage from the sup
ply canals. The concentration Of the
alkaline salt solution near the sur
face and the deposition of the alkal-
inc salts on the surface is the indir-
ect action. The remedy for the COM
bined evils is under-drainage which
removes the excess moisture from
the soil space. directly, while the al
kaline salts disappear as q matter OF
course, the action being just the re-
verse of that by which they made
their appearance.
BY lowering the water table, the
excess moisture already in the soil
is removed: fluctuations of the
ground water level are prevented,
and the percolation from subsequent
irrigation finds a ready means of es-
cape. Vigorous cultivation of the
soil followed by copious irrigation
permits of the teaching out Of the al
kaline salts by the downward move
Au0ut VI tu0 Wot0E. NC TOmOVoA VI
the excess moisture from the soil
spaces allows the air to enter and the
proper balance between air and
moisture Is maintained, while the
soil is made warmer. The greater
root space afforded actually increases
the amount Of available moisture and
the available plant food supply. Plow-
ing may be done earlier SO the grow
ing season is made both earlier and
longer.
While the direct action of under
drains is much the same in arid as in
humid regions, the ultimate results
desired and the methods of obtaining
them are vastly different. In the
humid sections drainage systems are
designed to remove given depth of
water from a given area in a given
period of time. This is usually ex-
pressed In terms of a certain frac.
ton of an inch in "a hours. In the
arid section the important thing -
to prevent fluctuations Of the ground
water level within the root zone.
which requires that the drainage sys-
rapidly as It falls and to care for per-
colating irrigation water and lateral
seepage from higher lying lands. Sys-
TENS must be designed, therefore, to
care for the maximum flow, and there
Is usually a continuous flow the year
round.
The root zone in the arid sections
extends to a considerable depth and
for ordinary conditions the ground
water level should not be permitted
to rise higher than five or six feet
from the surface. This calls for
drains six feet or more in depth,
which is greater than that usually
given to drains in the humid sections
| Where alkaline salts are present, il
is especially important that ample
depth be given, since these salts, be-
ing soluble, are concentrated at the
upper limit of saturation, which IL
often several feet above the free
water level. owing to the capillary
attraction of the soil.
The greater depth OF drains re.
quired and the necessity of providing
more generous capacity make the
unit cost of constructing drains IL
the arid section higher than in the
humid. Labor and material are alss
| AA6ACAs AAOpCIAy uCSA6ACO duu CdT0
fully constructed drains are effective
Throughout greater area, however
in the arid sections so that the cos
Of drainage is no more and Otter
less than in the humid sections.
! The drainage of irrigated lands hal
been reduced to a science and In
wolves many technical considerations
It is easy to make vital errors in loca
ton and design of drainage systems
and since the work is comparativel.
new and has received but little at
tention, there are but few men capa
BILE of handling the situation. Tn
great Importance OF the work is be
ing realized now, however, and mucl
careful study is being given the sub
] jejct. The construction of drainag
works is often extremely difficult an,
presents problems that only special
lists are competent to handle.
The first experiments to determine
whether or not lands injured by seep
age water and alkaline salts coul,
Se economically reclaimed were mad
In Utah and many successful demon
; STATIONS were carried out. As q re
Sn1t ~ tho Succoaa ~ thoso oxnApa