LAYING OFF CHECKS AND FURROWS 



173 



its bole, and that distant applications were likely to be wasted. 

 Years ago it was held that the lateral root extension of a tree was 

 equal to the spread of its branches, but recent investigations have 

 shown that under favorable soil conditions the root extension is 

 much 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 possibili- 

 ties : (1) Trees may be grown on hillsides too steep for other means 

 of irrigation unless the hillside be previously terraced; (2) the 



Combined check and furrow irrigation. 



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 appli- 

 cation 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, alter- 

 nating in direction so that the water, starting from the ridge above, 

 is dropped through a box, or otherwise let down, from the low end 



