272 Fertilizers 



a relatively greater abundance of the mineral elements 

 than do the clovers, which can acquire food through a 

 longer period. 



An application of 300 pounds to the acre of a mixture 

 of 200 pounds of acid phosphate and 100 of muriate of 

 potash, which supplies 25 pounds of phosphoric acid and 

 50 of potash, would, on medium soils, be regarded as a 

 sufficient annual dressing for clover crops; whereas, in 

 the case of the purely summer crops, the application 

 could be increased one-half with profit. In the case of 

 the summer crop, the phosphoric acid should be in a 

 soluble form, because it is not economy to depend upon 

 the conditions of climate, soil and season to change in- 

 soluble forms rapidly enough to provide for the con- 

 tinous feeding of the plant, while for the clovers, less 

 available forms may be used with advantage. 



Spring vetch. 



Spring vetch may be substituted for Canada field peas 

 in a mixture with oats ; and in the northern states, where 

 the pea-louse has been very destructive, it serves an 

 excellent purpose. It is sown in spring or early summer, 

 and does not survive the winter. The preparation of 

 soil and fertilization should be practically the same as 

 recommended for oats and peas. 



Hairy or winter vetch. 



Hairy vetch is used extensively as a cover-crop or green- 

 manure, and its use in combination with wheat or rye as a 

 forage crop is increasing rapidly. The chief advantage of 

 the use of hairy vetch with wheat or rye lies in the fact 

 that a larger crop of forage may be secured than when the 

 cereal is grown alone. The fertilization should be the 



