American Falls press. [volume] (American Falls, Idaho) 1907-1937, 1911-07-13
OF IRRIGATION
waterfall Should Be Uniform
Throughout the Ditch.
increased Productiveness Of Meadows
within Last Twenty-Five years
Que in Great Measure to
FertiIizing Sediment.

oSlluS d ultcn the rail-
whether great or small, should be uni
form throughout. Any diminution O,
the lall Will cause sediment to settle
ana NIL the ditch at that point. Thu
greater the fall of the ditch, espe
clally at the headgate, the greater will
De the amount of sediment drawn
from the stream. 1t Is customary tc
construct q dam in a stream at the
neadgate at right angle to the curren,
10 secure the full capacity at low
water. A shear dam apexed to the
headgate. IL the fall is light. will
throw more Of the finer silt into the
ditch. While II the fall is great II
Will too much coarse sand to
enter, writes e. A. Mitchell In the
Denver Field and Farm.
DISTINCTIONS, such as rock dams or
boards, driven in the bottom of a ditch
TO raise the water level SO as to
spread over meadow are wrong in
principle, as they always cause sedi-
ment to settle above the distractions.
The rock, sods or boards should be
placed at the side of the ditch to mar
row but NJ obstruct the middle or
bottom Of the channel. The irrigating
knolls or high places, the laterals
should not end at the highest point,
but extended through and beyond,
thus allowing sand and the heavier
particles of sediment to be carried
past and discharged on the slope.
Small vents should be III to conduct
water owe the high places. II the
ditch ends at the highest point, the
current ceases there and sediment Is
deposited where not needed, making
the knoll higher and more difficult Of
irrigation.
When there Is an abundance Of
in a stream it can be made
to play an important part in leveling
rough places on the fields If properly
applied. The vents cut in the main
bitches or laterals to spread the
water when the land is rough and un-
should diverge 1t at an acute
angle from the ditch. instead OF the
way Of at right angles.
will carry the sediment with the
current into the vents. thence out on
10 the meadows to finally settle In the
whereas If the vents are
cut at right angles, the force OF the
naturally deposits most of the
against the obstructing low
er side of the vent and soon fills
Itself. In fact to draw off all sedi-
nent possible every vent should be
tut on the oblique.
Any pioneer will have noticed the
meadows within the last twenty-five
ears. This In a great measure can
,e accounted for from the fertilizing
of deposited sediment. In 1889
cut over a barren coarse sand and
bar of a few acres in extent
n Gunnison county that then looked
O be worthless for hay land. This
'ame bar is now covered with black
ioil built up in the intervening years
md produces heavy crop OF wire
,rass. All erosive material carried
from the mountain sides con-
aims a more or less percentage of
phosphates, the very ssence Of a
concentrated fertilizer. A crude home
made analysis Of a hardened cake OF
;ediment one and one-haf inches
hick deposited in a depression on a
meadow last year gave the following
'esults under the glass:
Silt consisting Of decomposed ami
nal and vegetable humus. seven
ighths of an inch; finely eroded par
icles of volcanic rock, one-eighth
pch; sand and mica, one-half inch.
This cake was cut in circular form,
lgitated in a gold pan with water,
hen turned into a circular pan of the
anne diameter Of the cake OF sedi-
and allowed to settle and the
water to evaporate. A percentage or
and is necessary to maintain the
~,orosity of the soil for best growth
# plant life. In former times irriga-
high up near the sources OF
mountain streams was either not
Ieeded or practical. Copious rains in
lit countries where irrigation of the
over valleys was necessary. supplied
efficient moisture for the higher a
eys. therefore the value of the sedi-
entation near the source of treams
vas never studied. We yet too little
its value in the semi-arid
alleys of the great Rocky mountain
eeion. Plowed and cultivated fields
low i~rrigating waters to leach out
r wash away their best elements.