THE BASIN SYSTEM 169 



but recent investigations have shown that under favorable soil condi- 

 tions the root extension is vastly greater. It is not reasonable then to 

 restrict water or other plant food to the region chiefly occupied with 

 the stay roots and not the feeding roots of the tree, and it is a frequent 

 observation that basined trees do not do so well and that they show 

 distress sooner than those under systems which secure more complete 

 water distribution. 



To the basin system may, however, be conceded these possibilities : 

 ( 1 ) Trees may be grown on hillsides too steep for other means of irri- 

 gation unless the hillside be previously terraced; (2) the basins afford 

 an opportunity to use a very small stream of water by allowing it to 

 run for a long time in each basin, thus making a miniature reservoir at 

 the base of each tree; (3) for young trees a small amount of water 

 may sustain growth, while with other methods the same amount of 

 water would be almost wholly lost by evaporation or percolation, or 

 both; (4) the expense of wider application of water and the necessary 

 after-cultivation is obviated. 



In planting on hillsides, terracing is the foundation of the basin 

 system. Terraces are plowed and scraped out until they have width 

 enough to accommodate a line of basins and. a ditch at the foot of each 

 bank to supply them. The terraces are given a little fall, alternating in 

 direction so that the water, starting from the ridge above, is dropped 

 through a box, or otherwise let down, from the low end of one terrace 

 to the high end of the next, and so on until the stream reaches the bot- 

 tom of the slope. As a basin is reached it is filled and closed and the 

 water sent along to the next and so on. As these basins are usually 

 small and shallow thev are filled two or three times in succession at 

 each irrigation. 



Wherever water can be handled in contour ditches or furrows, ter- 

 racing should seldom be undertaken for commercial purposes. With 

 slopes which do require terracing, basins on the steeper parts are 

 largely made by hand labor, after plowing to loosen the whole surface, 

 and the operation consists in moving the earth from the upper side of 

 the tree so as to form a circular levee on the lower side, until the tree 

 stands in a level, roundish pan as large as can be made without too much 

 excavation and filling. As the slope becomes less the basins enlarge 

 and reach a diameter, finally, where the sides can be made by turning 

 a small horse or mule around the tree with a plow, the rim being further 

 raised and shaped by hand so as to hold 3 inches or more of water 

 without danger of breaking away. 



The basins are filled with a small stream by ditch or hose or pipe 

 line, according to the ground and notion of the irrigator. They are 

 filled at such intervals as the water supply admits or the growth seems 

 to need. The basin bottom is rarely disturbed. The cracking soil is 

 finally given another dose of water to close up its wounds ; meantime the 

 frequent surface soaking puddles the soil and the conditions unfavor- 

 able to growth arrive sooner or later, according to the disposition of 

 the soil to run together by water settling. Drying and cracking is 

 lessened by filling the basin with manure or rotten straw or other light 

 rubbish, or by a layer of coarse sand on the bottom. As the tree grows 

 the foliage shades the basin and thus reduces evaporation. 



