184 IRRIGATION FARMING. 



ing, the rill may be run within a foot of the trees, but 

 the water should never be allowed to touch the trunks. 

 Some horticulturists set out small fruits in rows four 

 or five feet apart longitudinally with the trees, while 

 others put such plants as raspberries and blackberries 

 in the tree rows themselves. The advantage of the 

 latter plan is that it affords more shade to the cane 

 fruits, but at the same time they are more apt to re- 

 ceive less water than they need, as cane fruits require 

 more water than is given to trees. By planting in the 

 open between the tree rows cane fruits may be irrigated 

 more frequently, and this can be done independently of 

 the trees themselves. 



As trees grow older year by year their furrows 

 should be carried farther away from the trunks, a good 

 rule being to keep them in a vertical line with the outer 

 tips of the branches. With full-grown trees the irrigat- 

 ing should be done with several parallel intermediary 

 rills, as pictured in Fig. 52. 



This system is much in use in the citrus groves of 

 Southern California. When the orchard is steep then 

 plant — not in straight rows, but lay out ditches with 

 a fall of one-quarter of. an inch to every rod, and plant 

 the trees along the ditches on the lower side. Pro- 

 fessor Blount of New Mexico lays out his orchards on 

 a grade of one inch to one hundred feet east and west, 

 and on a level north and south. He admits water at 

 the northwest corner of his quincunx plantation, and 

 by double furrows his trees are irrigated on all sides, 

 as displayed in Fig. 53, and by which means his root- 

 lets are uniformly watered. 



In all furrow operations it is best to allow the water 



