El Nuevo mexicano., 1917-10-18
INTERESTING TESTS BY STATE COL
LECE EXPERTS OF DUTY OF WATER
Estate College RuIletInl


These investigations are carried on
on what are locally known as Mesa
Plats, or bench lands adjacent to the
Rir Grande Valley. There being no
gravity system of water supply, water
is furnished these plats by pumping.
A good description OF the pumping
plant and irrigation system may be
found in Bulletin NO. SO published by
the New Mexico Agricultural Expert
ment Station. The plats are planted
to alfalfa and the data contained in
this article are based on the duty OF
water for alfalfa. These plats7 we're
seeded iii 1914, SO the data are for
the third years growth. s
Duty of water means the quantity
of water needed to mature crops. or
the relation between a given quantity
Of water and the area which it serves.
There are As plats OF land, which
are divided into four soil series, de-
pending on the depth of soil above
gravel stratum. The plats receive va
rious depths Of irrigation, regardless
of soil conditions. They are irrigated
every ten days. provided the percent
age Of moisture falls below Z percent,
which is near the whiting point.
The irrigation season commenced
March 10, when the first irrigation
was applied, and ended October 10,
when the last irrigation was applied.
AS far as the growth Of the alfalfa
plant was concerned, the growing sea-
son was a few days longer, as some
growth was made almost to the date
of cutting season, making a total of
220 days.
There were eight plats that receiv-
ed 2 inches of water at each irriga-
ton, and were irrigated 81 times dur
ing the season. The total number OF
times ali OF the 2inch plats were if.
rigated was 145. which averaged
1913 times each plat was irrigated.
Twelve p1ats received 8 inches Of wa
ter and the total number of times ir-
rigated was 145, which average of
14.92 times each plat was irrigated.
Eleven plats received 4 inches of wa
ter and were irrigated 142 times dur
ing the season, averaging 1856 times
each plat was irrigated. Nine Of the
plats received S inches of irrigation
water and were irrigated 100 times,
which averaged Hi times each plat
was irrigated during the season. Eight
plats in this investigation were fall
low, SO did not enter into the duty of
water calculations. All Of the plats
were irrigated their regular amounts
after each cutting. The largest
during the. first eleven irrieations, or
before the time when the rainy sea
son commenced iii July. tThree cut.
tings of alfalfa were harvested dur
ing this period.
During the season, six cuttings of
alfalfa were harvested. The dates
Of these cuttings were as follows:
First cutting, May Ssand 81; secondacut-
ting, June 8; third cutting, July 5;
fourth cutting, August 10; fifth cut
ting, September II, and sixth cutting,
October 23. The number and time OF
the cuttings show that the mesa lands
have a longer growing season than do
the valley lands. This condition would
naturally affect the duty of water.
The results shown above clearly
demonstrate that the plats which re-
ceived the least amount Of water at
an irrigation, but which received
more irrigations per season, gave a
higher duty than those which receiv'
ed more water at a single irrigation
but were irrigated not So often. This
was probably due to the fact that
when 5 inches of irrigation water is
applied at each irrigation, some Of it
is lost by ~percolating beyond the
reach Of the plant roots.
1t was found that the duty OF water
on plats which received, in Pinch irr1-
cation, an average of 36.25 acre
inches Of irrigation water, for an ir-
rigation season Of 220 days, was equiv
alent to 144.45 acres to the second-foot
of water. This is a high duty for al
falfa. While this is true and while
the water applied in the Pinch irriga-
lions proved to be most efficient IL
win be noted from the table that the
yield per acre vas secured
the 5-inch irrigations, and the