CULTIVATION. 



there deposit much mineral matter obtained from 

 the sub-soil, and thus render it richer. 



The retention of atmospheric manures is more 

 fully insured by the better exposure of the el 

 portions of the soil. 



The sub-soil often contains matters which are defi- 

 cient in the surface-soil. By the u*e of th-- 

 plow, they are rendered available. 



Sub-soiling is similar to under-draining in continu- 

 ing the tillering of grasses. 



When the sub-soil is a thin layer of clay on a sandv 

 bed (as in many parts of the country), the But 

 plow, by passing through it, opens a pa.^a-r f.-r v, 

 and often affords a sufficient drainage. 



If plants will grow better on a s..il six inches deep 

 than on one of three inches, there is im iva.-..n whv 

 they should not be benefited in proportion, by disturb- 

 ing the soil to the whole depth to which roots will 

 travel even to a depth of two feet. The minute 

 rootlets of corn and most other plants will, it' allow- 

 ed by cultivation, occupy the soil to a greater depth 

 than this, having a fibre in nearly every cubic inch of 

 the soil for the whole distance. There are very few 

 cultivated plants whose roots would not travel to a 

 depth of thirty inches or more. Even the onion semis 

 its roots to the depth of eighteen inches when the soil 

 is well cultivated. 



The object of loosening the soil is to admit roots 

 to a sufficient depth to hold the plant in its posi; 

 to obtain the nutriment necessary to its growth. 

 to receive moisture from the lower portions of the 



