THE SOIL AND THE PLANT 39 



If corn be planted, there should be a rotation in just the 

 same way. The corn plant, a summer grower, of course 

 uses a certain portion of the plant food stored in the soil. 

 In order that it may feed on what the corn did not use, 

 the crop following corn should be one that requires a some- 

 what different food. Moreover, it should be one that fits in 



FIG. 27. COWPEAS AND CORN OCTOBER 

 From photograph loaned by Director B. W. Kilgore 



well with corn so as to make a winter crop. We find just 

 such a plant in clover or wheat. Like the cowpea, all the 

 different varieties of clover have on their roots tubercles 

 that add the important element, nitrogen, to the soil. 



From these facts is it not safe to conclude that if you 

 wish to improve your land quickly and keep it always 

 fruitful you must practice crop rotation ? 



