272 SOILS 



the sunlight reflected from the water will not 

 burn the bark and leaves. The water should 

 not actually touch the trunks of the trees; citrous 

 trees are especially liable to be injured in this 

 way, contracting the "gum disease." Water that 

 seeps through at the lower end of the or- 

 chard, and which might run to waste, may be 

 collected in a foot ditch and used on the lower land. 

 All the ground on which young trees are planted 

 does not need to be irrigated. A distributing fur- 

 row may be plowed four to six feet away from the 

 row of young trees, with branch furrows circling 

 each tree. Water should stand in these from twelve 

 to twenty-four hours. The circle furrow is made 

 farther away as the tree gets older and eventually 

 merges into two straight furrows on each side. 

 The number of the furrows is increased gradually 

 as the orchard conies into bearing until the whole 

 area is laid off with narrow furrows four to five feet 

 apart. 



Occasionally fruit trees are irrigated by a system 

 of small pools or checks, a low retaining ridge being 

 thrown up around each tree with a "ridger," and a 

 certain amount of water allowed to stand within 

 until the soil has absorbed it. The chief objection 

 to this method seems to be that it tends to make the 

 roots develop near the surface and close to the tree, 

 and not to forage widely, though it is somewhat 

 more saving of water. More rarely fruit trees are 

 irrigated by flooding the whole ground. 



The vital point in irrigating tree fruits is to wet 

 the soil deeply and to make tillage go just as far as 

 it will in reducing the amount of irrigation. In 

 parts of California and Arizona it has been found 

 wise, on some deep soils, to irrigate deciduous fruits 

 never citrus fruits in winter, as this may 



