ROTATION OF CROPS. 179 



Principles of Rotation. 



LEGUMES IN A ROTATION. 



One of the most profitable plans of rotation is a system of 

 cropping that includes a legume for the supply of nitrogen, which 

 is one of the most expensive elements essential to plant growth. 



Each of the different legumes seems to be adapted to certain 

 climatic conditions and soil types. The principal legume used 

 in the rotation of crops in the corn belt is red clover, with the 

 exception of Kansas and Nebraska, where the key to rotation 

 is rapidly coming to be alfalfa. 



In 1910 there were nearly 3 million acres of alfalfa grown 

 west of the Missouri River while there were perhaps less than 

 half a million acres grown east of that territory in the U. S. 

 Red clover is grown principally east of the Mississippi River and 

 North of the Ohio River. In the southern states the principal 

 legume used in rotation with cotton is the cowpea. The soy- 

 bean is rapidly increasing in acreage in the southern States and 

 in the territory just north of the Ohio River. Crimson clover is 

 grown along the Atlantic Coast from central New Jersey to 

 Georgia. 



The following system of rotation has generally been adopted 

 where each of the following is a leading crop : 



CORN. 



Four Year Rotation. 

 Corn Oats Wheat Clover 



ALFALFA. 



Six to Eight Year Rotation. 

 Alfalfa (3 to 5 yrs.) Corn Corn Corn Manured 



BARLEY. 



Three Year Rotation. 

 Barley Clover Corn 



RYE. 



Three Year Rotation. 

 Rye Clover Corn 



