CHAPTER FOUR 



SOIL FERTILITY AND ITS PRESERVATION 



... If vain our toil, 

 We ought to blame the culture, not the soil. 



ALEXANDER POPE 



Worn-out " A RICH soil makes a prosperous people." This is 



a very true saying, but it is not easy to keep a soil rich. 



There are many farms, especially in the eastern part of 



the United States, which once produced abundant crops, 



but which are now practically deserted because the 



fertility of their soils has become so low that the crops 



which can be raised are too poor to be profitable. Such 



farms are called " worn-out farms." In the Middle West, 



where the land has been brought under cultivation more 



recently, the soil is still rich and the crops are abundant ; 



but these farms will also become worn out in time, unless 



proper methods of farming are employed (Fig. 22). 



What the The fertility of wild land. For perhaps thousands of 



Hitlers years before the coming of white settlers, luxuriant 



found crops of wild prairie grass grew each year upon the plains 



of the Middle West, the soil probably becoming better, 



not poorer. What grass was not eaten by the buffaloes 



and antelopes was swept away by prairie fires after it 



The effect of became dry. When settlers first began to break sod, 



cropping ^^ found ^ goil bjack with r j c h ness Whenever 



sufficient rain fell, abundant crops were secured. * Before 

 many years, however, farmers began to find their crops 

 falling off and the land requiring fertilizers. 



How could this land produce a natural crop for cen- 

 turies without loss of fertility, while it showed the effect 



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