VERTICAL FARMING 



37 



U. S. D. A. 



A BADLY ERODED HILL 



much effort and long exposure to weathering before the plant 

 food reaches a satisfactory state of availability. Gentle, slow 

 rains are always preferable, because they have more time to 

 soak into the soil, but as the intensity of rainfall is beyond the 

 control of the farmer, he must fortify his soil against attacks 

 of erosion due to heavy precipitation or large amounts of rain- 

 fall in a short time. The answer is to get the water down into 

 the soil before it can run off. It is a difficult matter to do this in 

 a big wash, where thousands of barrels of water are coming 

 down, but these large washes are started by little trickles of 

 only a few spoonfuls further up the hill. These little trickles 

 start because the soil is too tight for the water to enter. The 

 surface may be sealed over by a little crust or there may be 

 plow sole, tight clay, or hardpan deeper down which limits the 

 soils absorption to the immediate surface. The correction of 

 such conditions prevents the wasting of the valuable soil into the 

 drainage courses. The surface crust can be destroyed with 

 even the lightest tools, and a deep shattering by blasting will 

 open up the subsoil so that it will be able to absorb hundred of 

 gallons of water, where before it took but sparingly. 



