184 The Commercial Apple Industry 



est ridge. The use of concrete or other underground 

 piping, together with standpipes, for carrying the water 

 to the upper end of the furrows is unquestionably the most 

 efficient system of distribution. Whether such an invest- 

 ment will prove economical depends on the scarcity of 

 water and the returns obtained from the land. The 

 earthen ditch or cheap wooden flume may be the more 

 economical. 



The actual application of water to the soil is usually 

 accomplished by means of furrows or rills. The length 

 of the rills ordinarily varies from 200 to 600 feet, depend- 

 ing on the slope and character of the soil. With sandy 

 soils or steep slopes, the rills should be short and narrow 

 at the bottom in order that washing will not occur or over- 

 irrigation of the upper end of the tract at the expense of 

 the lower lands. With gentler slopes and heavy soil, the 

 furrows may be very much longer and also wider at the 

 bottom, in order to promote percolation. The depth of 

 furrows usually varies from four to six inches, although 

 there is a tendency towards deeper rilling, eight inches 

 being recommended by some in order that the first few 

 inches of surface soil may be kept partially dry. When 

 the top of the soil is moist, there is excessive loss through 

 evaporation. If the land is very steep, a very small stream 

 is necessary in order to prevent washing. With light 

 porous soils the furrows are made shallow, narrow at the 

 bottom and relatively close together, the water being run 

 through quickly and under a heavy head of water. 



The number of furrows in a tree row varies from two 

 to six, five being the most common. (See Plate X.) The 

 irrigator tries to get the first row within three feet of the 

 tree row and spaces the remaining ones at a distance of 



