52 



BULLETIN 1026, U. S. DEPARTMENT OF AGRICULTURE. 



and other row crops are irrigated by furrows between the rows. The 

 method of flooding from field laterals, used on nearly two-thirds of 

 the total irrigated area of the valley, does not vary essentially from 

 the general practice. Supply ditches are located at the margin of the 

 field; small laterals from these extend into the field; and through 

 openings in these field laterals the water flows out over the land. In 

 general, the effort is so to fit the layout of the supply ditches and 

 field laterals to conditions of soil and topography that with a head 



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2 1 6 8 10 12 11 16 ■ 18 1 

 ACRES rnRIGA-TEID PER 24-MOLJR DA.V | 



Fig. 4. — Relation betsveen the headj used and the area irrigated per 24-hour day 

 for flood ajid furrow irrigation. 



of from 2 to 3 second-feet a thorough irrigation may be secured 

 with a minimum expenditure of time and work. For this reason the 

 details of practice vary almost with the number of fields. 



Supply ditches are carried along the margin of the field or follow 

 ridges, the former location being preferred if conditions are at all 

 suitable as less space is required and cultivating and harvesting ma}' 

 be carried on with less difficulty. Practically all these ditches are 



