3O4 SOILS AND FERTILIZERS 



Temporary methods of farming, as exclusive grain raising, 

 can be followed for a short time on new soils ; but it is 

 desirable that each type of soil should be subjected to a 

 judicious system of cultivation, fertilizing, and cropping 

 rather than to the production of one or only a few mar- 

 ket crops at random. The selection of the crops and 

 their utilization for market or feeding purposes should 

 be determined mainly by the system of farming that is 

 most adapted to the soil of the farm, and the farm 

 should be managed largely with the view of maintain- 

 ing the fertility of the soil. 



359. The Inherent and Cumulative Fertility of Soils. 95 

 There is present in nearly every soil a variable 

 amount of inherent fertility resulting from disintegration 

 and other changes to which soils are subject. In some 

 long-cultivated soils the amount of fertility produced 

 annually by weathering and natural agencies is sufficient 

 to yield from ten to fifteen bushels of wheat per acre. 

 This does not represent the maximum crop-producing 

 power of the soil, but simply the inherent or natural fer- 

 tility. When the natural fertility is reenforced with farm 

 manures and other fertilizers, culmulative fertility is 

 added and maximum yields are secured. In many soils 

 there are large amounts of cumulative fertility or resi- 

 dues from former applications of manure. The crop- 

 producing power of a soil is dependent upon both the 

 inherent and the cumulative fertility, as well as upon 

 the mechanical condition of the soil. In the production 



