THE WATER OF SOILS. 



243 



Basin Irrigation. In this method of irrigation, practiced 

 only in the case of trees and sometimes vines, and when water 

 is scarce, a wide circular furrow or basin is excavated around 

 each trunk and water is run either from one to the other, or 

 sideways from a furrow laid along the rows. The water 

 thus applied of course percolates immediately around the trunk 

 first, and in practice is found to follow also the large roots; 

 so that it goes precisely where it is most wanted, besides form- 

 ing a vertical body of moist soil reaching to considerable depth, 

 where it is most desirable that the root system should follow. 

 By this deep penetration to natural moisture in the depths of 

 the soil, comparatively small quantities of water produce very 

 marked effects. 



On the same principle, the grape vines which bear some of 

 the choicest raisins of Malaga on the arid coastward slopes, 

 are made to supply themselves with moisture, without irriga- 

 tion, by opening around them large, funnel-shaped pits, which 

 remain open in winter so as to catch the rain, causing it to 

 penetrate downward along the tap-root of the vine, in clay 

 shale quite similar to that of the California Coast Ranges, and 

 like the latter almost vertically on edge. Yet on these same 

 slopes scarcely any natural vegetation now finds a foot-hold. 



Similarly the " ryats " of parts of India water their crops 

 by applying to each plant immediately around the stem such 

 scanty measure of the precious fluid as they have taken from 

 wells, often of considerable depth, which form their only 

 source of water-supply. Perhaps in imitation of these, an in- 

 dustrious farmer has practiced a similar system on the high 

 benches of Kern River, California, and has successfully grown 

 excellent fruit for years, on land that would originally grow 

 nothing but cactus. Sub-irrigation from pipes has been applied 

 in a similar manner. 



A combination of the furrow- and basin-irrigation system is 

 sometimes practiced in southern California by drawing the 

 furrow so as to bring the tree within a square, one side of 

 which is left closed. The same result may be accomplished 

 by plowing cross furrows at right angles near the tree and 

 then placing checkboards so as to force the water along the 

 rows, zigzagging, on three sides. 



The basin irrigation of orchards was originally largely 



