54 
BULLETIN 1026, U. S. DEPARTMENT OF AGRICULTURE. 
next. If the land is rolling, the laterals are spaced to follow the 
ridges and water is turned down both slopes. On very uneven land 
it is customary to build the field laterals to high points where the 
water is turned out to be directed here and there by temporary dikes 
thrown up with a shovel. To get the water from the lateral to the 
field cuts are made in the banks at intervals of from 5 to 20 feet and 
the water is forced through by checking the lateral farther down 
with a canvas, metal, or dirt dam. 
APRIL 
10 20 
i 
MAY 
20 
JUNE 
10 20 
i 
JULY 
20 
AUGUST 
10 20 
SEPTEMBER 
10 20 
19 
16 
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10 
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1 
II 
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1 
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S 3 
1 
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1 
1 
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1 
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19 
17 
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111 
Fig. 
6. — Irrigation of grain. Water requirements of 622 acres in 1916 and 
of 429 acres in 1917. 
By far the greater part of the area irrigated by the furrow method 
is in sugar beets and potatoes, but corn, beans, peas, and truck are also 
irrigated in this manner. In the valley irrigation by this method 
consists in plowing furrows between the rows and running water 
down these furrows from notches cut in a ditch at the head of the 
field. Furrows are made in each middle with a shovel or other suit- 
able plow and are especially deep for potatoes. To secure an even, 
fast irrigation, furrows are usually about 500 feet long, but the type 
of soil, slope of land, and amount of water available will cause a wide 
