MAINTAINING SOIL FERTILITY 315 



been seriously impaired in fertility. But the larger 

 consideration of maintaining soil fertility for other 

 generations surely deserves serious thought from the 

 farmer of to-day. In any case it is likely that he 

 will have the subject brought to his attention by 

 self interest. The effects of pursuing a system of 

 farming that continually takes from the land and 

 returns nothing or little to it may be seen within 

 a generation, or even within a decade. Each year 

 thousands' of American farmers are radically 

 modifying their systems of husbandry for the pur- 

 pose of maintaining the fertility of their farms. 

 Sometimes this must be done, apparently, at the 

 expense of self interest, at least for a few years. 

 Some of the crops that have paid best either must 

 not be grown at all or grown less frequently. But 

 a series of years may tell another story. 



DIVERSIFIED FARMING 



The number and kinds of crops grown are largely 

 determined by the distance to the market. Eastern 

 farmers, who are close to large markets, grow a 

 greater variety of crops than Western farmers. Cot- 

 ton in the South, corn in the Central States and 

 small grains in the West are the most conspicuous 

 examples of single-crop farming in the United 

 States. There are many small single-crop areas, as 

 Aroostook County, Maine, which is devoted largely 

 to the culture of potatoes. Single-crop farming 

 does not necessarily mean that but one crop is 

 grown; it may mean that one main crop is grown 

 with a few secondary crops. Small grain farming, 

 even though wheat, oats, and barley are grown, 

 would be considered, in its effect on soil fertility, as 

 single-crop farming. 



