VERTICAL FARMING 



33 



U. S. Rec. Service 



IRRIGATION DAM THE EXPENSIVE METHOD OF STORING WATER 



FOR PLANTS 



through evaporation. Where this practice has been carefully 

 followed, good has resulted, but ordinarily the depth to which 

 plowing is possible is insufficient to reach the zone of the great- 

 est trouble. Others have gone further and plowed deeper, using 

 heavy tractors with subsoil plows. The results obtained have 

 been variable, and it is quite evident that the efforts along this 

 line, while well conceived and of benefit, have fallen short of 

 their mark by not disturbing the soil to a sufficient depth. 



In most cases of resistant soils, the trouble is at a considerable 

 depth, in fact, below the depth that could possibly be reached 

 by any form of plow. For relief then, there is nothing prac- 

 ticable but a rational use of a subsoiling explosive. This, like 

 the subsoil plow, is used when the subsoil is dry, so that the 

 force of the explosion will shatter and pulverize the subsoil 

 rather than pack it into a more impervious mass. Usually this 

 is in the late summer and early fall, when the plants have 



