Graham guardian., 1905-03-03

The alkali Of the Gila valley is
confined for the most part to the
Maricopa silt loan. The areas in
which the salts prevail to d danger
Gus extent occur only il a half
dozen or so places, usually follow
ing the boundaries of the ALaricopa
silt loan and covering fr,m one
half square mile to three square
miles each.
The position of these areas, and
the average salt CONTEXT to the
depth of six feet, may be ascer'
tanned by reference to Plate l.
The proportion to alkaline soil as
compared with the total area sur
veyed is considerable. The dam
age thus far done is, however, in
many cases slight, the alkali and
seepage conditions upon the whole
being very much better than in
many of the irrigated districts of
the west. The conditions, how
ever, demand careful attention to
prevent an extention of the areas
affected bo seepage water and the
further deterioration of lands al.
ready more or less alkaline Over
considerable proportion of the
area containing from 0.20 to 0.40
per cent most of the alkali exists
in the lower part of the six-foot
section, .t'fLlfa, when once start
ed, makes nearly normal growth
on these areas, and in some cases
does we'll. In soils in which the
salt content does not exceed 0:40
per cent, sugar beets, sorghum, and
alfalfa may be grown with profit;
provided precautions are taken In
starting the crop. Often moder
ately heavy irrigation before seed
ing will result in the movement of
the surface salts toward the sub
soil By the time they return to
the surface the crop may have
sufficient stand and vitality to en-
dure the injurious effects of the
salts, Even slight alkali accumu-
lations, however, are always a
source of danger, and soils in
which they exist should be care
fully handled.
Sodium chloride, or common
table salts, is of common occur
renee in the Gila valley area and
forms large proportion of the
alkali salts of the region, both in
the soils and in the underground
waters. While less harmful in its
effect upon plant growth than
some of the other salts, it is in alb
normal quantities dangerous sub
stance.
Sodium sulphate also occurs
here in large amounts, and with
sodium chloride forms by far the
greater proportion Of the total
alkali salts of the area. Upon the
surface it sometimes appears as a
white, powdery crust, readily
blown into the air, and has an ir-
ritating effect upon the mucous
membrane of the throat and nasal
passages.
These two salts form practically
all the white alkali" of this area,
the sulphates, chlordes, and phos-
pilates of calcium, potassium, and
sodium, respectively, occurring in
small amounts,
Bicarbonate and carbonate of
sodium are also common alkali
salts, appearing to some extent 10
the Gila valley area. The former
is classed with the less harmful of
the alkah salts, 1t may, however,
by giving rise to the sodium car.
Donate, be indirectly capable of do
ing great injury.
Sodium carbonate, or "black
alkali," as it is commonly called,
is one of the most dangerous salts.
1t is, strictly speaking, an
"alkali." corrodine and destroying
both the humus or vegetable mat
ter of the soil and the tissues of
growing plants. In its effects it is
several times more deadly than
either the chloride, sulphate, or
bicarbonate of sodium Its action
in corroding and dissolVing the
organic matter of the soil iinparts
to the moist soil surface, and to
pools of seepage water where it is
concentrated, an inky black color.
Although sodium carbonate is fre
quently detected both in the soil
and water of the area, it occurs in
large or dangerous quantities only
in few spots, too small to be
shown on the map, where the total
salt content is greatest. Sodium
carbonate may in poorly drained
areas, be formed by the evapora-
ton of bicarbonate solutions from
the surface, carbon dioxide being
slowly given off and the salt re-
naming in the less carbonated
form, or as the "normaI salp.
Hence the matter Of drainage be-
comes doubly important in areas
in which the comparatively harm
less bicarbonate of sodium pre-
walls.
In the Gila valley area the sub
soils of the heavier types carry in
the aggregate great quantities of
the alkali salts. Fortunately,
however, natural DRAINAGE IS good