Lincoln County times. (Jerome, Idaho) 1911-1919, 1911-07-13
PLAN OF IRRIGATION
Waterfall Should Be Uniform
Throughout the Ditch.
Increased ProductIveness OF meaoo"'
Within Last Twenty-Five years
Due in Great Measure 10
FertiIlzine Sediment

In constructing a ditch the 'aii'
whether great or small shouiu oe W."
form throughout. ANY dimlnuuoh VI
the fall will cause sediment to settle
and ill the ditch Ut that point i"'
greater the fall OF the ditch' espe
cially az the headgate. the srea'ei VIZ
no tho amount OF sediment drawn
from the stream. It is customary 10
construct a dam IN a stream at the
hsndgate M right angle TO the current
TO secure the full capacity at W"
water A shear dam apeAed 10 'ho
headgate. If the fall is light VIII
throw more of the finer silt into the
ditch While II the fall Is great IL
will cause too much coarse sahu 10
enter writes E. A. Mitchell in the
Denver Field and Farm
Distractions, such as rock dams or
boards. driven in the bottom OF often
70 raise the water level so as TO
snread over meadow are wrong IN
principle. as they always cause seol'
ment TO settle above the distractions
The rock, sods or boards should De
placed at the side OF the ditch 10 mar
row but not obstruct the middle OF
bottom OF the channel. The irrigating
knobs 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 cut to conduct
water over 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
sediment In a stream II can be made
to play an important part In leveling
rough places on the fields II properly
applied. The vents cut In the main
bitches or laterals TO spread the
water when the land is rough and I'M
even should diverge It at an acute
angle from the ditch, instead OF the
customary way OF at right angles.
This will carry the sediment with the
current into the vents. thence out on
to the meadows to finally settle In the
depressions, whereas II the vents are
cut at right angles. the force OF the
current naturally deposits most OF the
sediment against the obstructing low
er side of the vent and soon Nils
Itself. In fact to draw of all sedi-
ment possible every vent should be
cut on the oblique.
ANY pioneer will have noticed the
Increased productiveness OF native
meadows within the last twenty-five
years. This In a great measure can
be accounted for from the fertilizing
effect OF deposited sediment. In 1883
cut over a barren coarse sand and
gravel bar OF few acres in extent
In Gunnison county that then looked
to be worthless for hay land. This
same bar is now covered with black
soil built up In the intervening years
and produces heavy crop OF wire
grass. All erosive material carried
down from the mountain sides con
tains a more or less percentage oi
raw phosphates. the very essence OF {
concentrated fertilizer. A crude home
made analysis OF hardened cake o
sediment one and one-half inche,
thick deposited in depression on ;
meadow last year gave the following
results under the glass:
Silt consisting Of decomposed AMI
NAL and vegetable humus. seven
eighths of an inch; finely eroded par
ticles OF volcanic rock. one-eighti
inch; sand and mica, one-half inch
This cake was cut in circular form
then turned into a circular pan OF thu
same diameter OF the cake OF sedI
ment and allowed to settle and tn,
water to evaporate. A percentage o
sand is necessary to maintain tn,
porosity Of the soil for best growtl
Of plant life. In former times irriga
ton high up near the sources o
mountain streams was either no
needed or practical. Copious rains n
silt countries where irrigation OF tn,
lower valleys was necessary. supplied
sufficient moisture for the higher val
leys. therefore the value OF the sedl
mentation near the source OF streami
was never studied. We yet too littl,
understand its value in the semi.ari,
valleys OF the great Rocky mountain
region. Plowed and cultivated field
allow irrigating waters to leach on
or wash away their best elements.