CHAPTER X 

 THE COWPEA 



A Southern Legume. --The soils of the cold 

 north are protected from leaching during the 

 winter by the action of frost. The plant-food is 

 locked up safely for another year when nature 

 ceases her work of production for the year. Far- 

 ther south, in the center of the corn belt, there are 

 leaching periods in fall and spring and oftentimes 

 during the winter, but winter wheat thrives and, 

 in ordinary crop-rotations, covers much of the land 

 that might otherwise lose plant-food. As we pass 

 from the northern to the southern states, the 

 preservation of soil fertility grows more difficult 

 and at the same time the restoration of humus 

 becomes easier. The heat makes easy the change 

 of organic matter to soluble forms, and the 

 rains cause waste, but the climate favors plants 

 that replace rapidly what is lost. In the work of 

 supplying land with fertility, directly and in- 



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