104 THE PRINCIPLES OF AGRICULTURE. 



cultivation and success in farming depend largely upon 

 the plow and the use made of it. 



Deep Plowing. As a general rule, ground is not 

 plowed to a sufficient depth. The soil below that part 

 which is stirred in cultivation is generally of little direct 

 service to crops. 



The subsoil is often too hard to allow roots to pen- 

 etrate it freely. As it is buried away from the atmos- 

 phere, the chemical changes which would convert its 

 materials into plant food are very slow. 



By bringing it to the surface, and mixing it with the 

 fertilizers and fertile soil, these materials are made more 

 rapidly available. 



Economy in farming requires that large crops shall be 

 produced upon small areas. By deepening the cultivated 

 soil, and thus enlarging the extent of space and increas- 

 ing the supplies of food available to the roots of plants, 

 we attain this end. 



Deep tillage, also, has much to do with regulating the 

 supply of moisture. In wet seasons it affords drainage 

 by providing more space for the surface water to pass 

 into the porous soil beneath. 



In a time of drought, as the roots of crops have been 

 able to extend themselves more deeply into the soil, they 

 are able to obtain a supply of moisture, and are not so 

 much injured by the drying of the surface. 



While deep plowing has these advantages, there are 

 some cautions to be observed. To plow land at first 

 much deeper than ever before, would bring to the surface 

 a large quantity of crude soil. Unless a great amount 

 of fertilizer is applied, this poor soil is liable to injure 

 and retard the groAvth of young plants before their roots 

 can penetrate to the better soil below. This difficulty 



