The Greeley tribune., 1912-12-19
DRIVING OUT ALKALI

Everybody knows that extensive
regions of the semi-arid west are
sterile on account of the presence
of an excess of alkaline salts-pop-
ularly known as "alkali'-in the
surface soil; but probably few peo-
pie living away from the region in
question realize to how great an
extent this evil has been increased
by irrigation. A startling state of
affairs is revealed by r. A. Hart, a
United States drainage engineer, in
recent discussion of the alkali
problem.
Formerly socalled alkali soils
were confined to recognized deserts
and to scattered spots elsewhere,
and attracted but little attention.
Now it is found that nearly all reg
ions of the west in which irrigation
has been practiced for a consider
able length of time show more or
less deterioration on account of al
kali. Mr.. Hart says: Broadly
speaking, there is not a valley in
the west in which the injury has
not been felt, and in some of these
large portion of the lands form
erly cultivated are now idle or used
only for wild pasture"
Everywhere farms have become
unproductive and have been aband-
oned. Heretofore it has been a
comparatively simple matter for the
farmer, having been thus driven
from his land, to take up raw land
elsewhere; but now the opportun-
ity for expansion is practically
gone, and it is time to consider seri-
ously the second reclamation OF
the desert.
Alkali salts result from the dis
integration of the rock materials
common to all parts of the world,
by heat and cold. ice, water, wind,
vegetation and other agencies.
Their formation is by no means
peculiar to the arid regions Here,
however. the rainfall is not heavy
enough to carry away the dissolved
alkali to the streams and ultimately
to the sea; moreover excessive
evaporation of whatever water the
soil contains results in abundant
deposits of the salts held in solu-
tion.
The effects of irrigation are Pc
culiar. and at first sight self-con-
Trajectory. There is general
tendency on the part of the farm
ers to over-irrigate. In the early
stages of the process the water per-
colates downward through the soil
and by teaching out the alkaline
salts from the levels to which the
roots of plants extend makes agri-
culture possible. The water sup
piled by irrigation. however, in con-
trast to rain, contains an abundance
of alkali in solution, and an excess
of this water leads to loss by evapo-
ration and the deposit of the con-
tanned salts.
The most serious effect of over
irrigation is the filling up of the
ground water reservoir and the rise
of the water table. 1t is well known
that soils are saturated several feet
above the free water level by the
action of capillary attraction, and it
is found that the alkaline solution
is concentrated near the upper limit
of saturation. AS the water table
rises the concentrated alkaline So
luton precedes it by few feet 1t
is only question of time before the
alkali zone of the soil is thus push
ed upward to the root level of
plants and vegetation is killed The
proximity of the ground water table
y,
so that the destruction of plants
may also be due tothis cause. The
remedy is simple, and the only rea-
son that ii has not heretofore been
generally applied is that it has been
| cheaper to take up new land than
to reclaim that which had become
alkaline. 1t is necessary only to
lower the water table, then leach
out the land with abundant irriga-
tion for time, and afterward re-
strict the amount of irrigation
water within sane limits. Mr.. Hart
concludes:
Good under-drainage is the only
cure for the difficulty, and it's ef-
| fectiveness is best demonstrated by
the vast operations now being con-
Quoted. The second reclamation OF
| the desert is at hand"
This process has been carried out
on the largest scale in Egypt, where
| in ten years nearly 250.000 acres OF
| alkaline land We're drained and re-
| stored to cultivation. The United
| States department of agriculture
has made substantial progress with
similar operations in our western
states.-Country Gentleman.