Irrigation 185 



three to four feet apart. Shallow rills require closer spac- 

 ing. With very young trees, a furrow on either side of 

 the tree row is usually sufficient. This plan is also fol- 

 lowed with mature trees where a shortage of water occurs 

 in order to get over as much land as possible. Ordinarily 

 with full bearing trees, the entire surface of the land is 

 watered. 



The most common implements for making furrows are 

 the six-foot cultivator, with the three shovels attached and 

 the single shovel plow. The latter implement is frequently 

 used for making the furrows close to the tree rows. A 

 single furrowing during a season usually suffices when the 

 orchards are in alfalfa, although occasionally the orchardist 

 finds it necessary to open up the rills late in the season. 

 Cultivation between irrigations entails the replacing of the 

 rills. 



The operation of turning the water on the land is termed 

 a " set." It is usually necessary to make several sets if 

 the orchard is large. The irrigator turns his entire head 

 of water into a few furrows and allows it to run from 

 twelve to seventy-two hours, varying with the type and 

 condition of the soil. The water is allowed to run, until 

 by a slow lateral movement it saturates the soil between 

 the furrows. "When the orchardist finds that sufficient 

 saturation has taken place, he turns the water into another 

 portion of the orchard and so on until the entire area is 

 irrigated. 



Flooding is practiced in a limited way and under this 

 system the water seeks its own course over a strip usually 

 a few tree rows wide. This practice has been largely 

 superceded by furrowing. 



