PLANTS OF THE CLOVER FAMILY. 75 



In some sections it is common to grow medium 

 red clover, corn or potatoes and small grain in a three 

 years' rotation. When the conditions are suitable 

 the plan is an admirable one. But few methods of 

 crop production will compare with it in the easy 

 maintenance of soil fertility and in the profits that 

 grow out of the system. The other leading kinds 

 of clover, however, are not so well adapted as the 

 medium for such a rotation. The mammoth does 

 not produce a second growth, for being plowed under, 

 as does the common red. The alsike is perennial in 

 its habit of growth, and the crimson is better adapted 

 to another form of rotation, as will be shown below. 



The medium and mammoth clovers may, never- 

 theless, be made to fit into any kind of a rotation. 

 The aim should be to grow them at short rather than 

 at long intervals in the rotation, and for several 

 reasons. First, as previously intimated, they have 

 great power to enrich the land by depositing in it 

 nitrogen drawn from the air; second, they have 

 much power to gather supplies of phosphoric acid 

 and potash in the subsoil, much of which is deposited 

 again in the cultivable strata; third, they improve 

 the mechanical condition of the land by the abun- 

 dance of the vegetable deposit contained in the roots, 

 and, fourth, the humus thus supplied greatly 

 increases the power of the land to hold moisture, 

 whether it comes from above or below. There is 

 probably no other plant grown that is capable of 

 exercising so beneficent an influence on farming. 



The place for crimson clover is, properly speak- 

 ing, that of a catch crop. It is usually grown as the 

 antecedent of or the consequent to some other crop 



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