IRRIGATION 
12-inch pipe: 
Slope 1 in 75, discharges 6.3 sec. ft 
Slope 1 in 150, discharges 4.5 sec. ft. 
16-inch pipe: 
Slope 1 in 100, discharges 11.7 sec. ft. 
Slope 1 in 250, discharges 7.25 see. ft. 
The gradient or slope of a pipe line 
refers to the slope of a straight line 
drawn between the intake of the pipe and 
the center of the discharge end. This line 
is technically called the hydraulic grade 
line. The pipe may be laid at any dis- 
tance below this line, but never above 
it. 
There are many variables entering into 
a determination of the actual duty of 
water. In general terms, however, it may 
be said that seldom will one second-foot 
be required for 60 acres, more often 100 
acres, and with economy where ordin- 
ary crops of wheat and corn are grown 
as many as 200 acres. 
As heretofore suggested, the steeper 
the grade the greater will be the amount 
of water a given size of pipe will carry, 
and hence a small pipe on a steeper grade 
will often carry as much water as a 
comparatively large ditch which always 
must be built sufficiently high to dis- 
charge onto the adjacent fields. This 
means a loss of cultivated area, and of- 
ten serious inconvenience to the irrigator. 
With buried pipes carrying water under 
pressure, these annoyances are avoided 
entirely, and the water may be delivered 
with facility upon any portion of the 
field. If wood pipe be used gate valves 
can be introduced with decided economy 
and convenience. In addition to this, 
they can always be closed when the neces- 
sary water has been applied, and thus the 
pipes can always be kept full, whence 
economy and conservation. A full pipe 
means a saturated pipe, and when the 
wood of the pipe is saturated there can 
be no rot. Experience has proven be- 
beyond doubt that rot is prevented by 
saturation. 
Basis for Selling 
It is always much more satisfactory 
to sell water based on a price for the ac- 
tual water used, rather than to sell it on 
the basis of acres irrigated. The latter 
method invites waste on the part of the 
user, since it is but human nature for 
1173 
wees Ditech requires 3.5 ft. bottom width 
vec eee Ditch requires 5.0 ft. bottom width 
seen Ditch requires 4.0 ft. bottom width 
the irrigator to draw on the water sup- 
ply up to a point where he feels satis- 
fied he is getting all he pays for. By the 
other method he pays for exactly what he 
gets. The temptation being removed, the 
loss from this source is eliminated and 
the irrigable area correspondingly in- 
creased. In fact, some states, notably 
Idaho, have a law requiring all charges 
for water to be “based upon the quantity 
delivered to consumers and not in any 
case to depend upon the acres irrigated.” 
With a pipe system it is easy to deter- 
mine the amount of water used. 
SYSTEMS OF IRRIGATION 
There are several systems of irriga- 
tion, each having some merit, and per- 
haps each one best under certain circum- 
stances. 
Flood 
The first is the system of flooding 
which is used in the rice fields with a 
degree of success that justifies its con- 
tinuance. Experience seems to have 
proven that this system is the best for 
the conditions under which rice is grown, 
and perhaps no other system could be 
adopted that would be so practical for the 
growing of this crop. 
Check 
The second is the check system, which 
makes the ditches in squares around the 
trees and overflows the ground inside of 
the squares or causes the water to per- 
colate through the soil in the ditches. 
Furrow System 
The third is the small furrow system, 
which makes small laterals about three 
feet apart and allows the water to run 
from the main lateral on the high point 
of the land in small streams. From 
these small ditches the water percolates 
through the soil until the whole surface 
soil is wet. It is presumed that when the 
surface shows that the water has per- 
colated until the dampness from each 
stream meets in the center one and one- 
