BARNYARD, STABLE, GREEN MANURES 113 



Principal Green Manuring Crops. — The principal crops grown in 

 the United States for green manuring purposes are red clover, alfalfa, 

 alsike clover, crimson clover, cowpeas, Canada peas, soy beans, vetch, 

 velvet bean, Japan clover, sweet clover and bur clover. In addition to 

 these, beggar weed, peanuts and velvet bean are also used in the South. 

 These are all legumes, and are decidedly preferable to non-legumes under 

 most conditions where green manures can be used. In the North, where 

 the winters are severe, rye and occasionally wheat are used for this pur- 

 pose. Buckwheat, which is a summer annual, is also sometimes used. 



Rye Turned Under for Soil Improvement. 



When heavy green manuring crops are turned under allow two weeks or more to 

 elapse before planting succeeding crop. 



The characteristics and the requirements for these crops will be dis- 

 cussed in Book II of this work. 



On poor soils lime and the mineral fertilizers may be used with profit 

 in the production of a green manure crop. This will stimulate the crop 

 to a greater growth, and when it decays in the soil the elements applied 

 will again become available for the crop that is to follow. 



The composition of the legumes used for green manuring varies con- 

 siderably, depending upon local conditions, character of soil and the stage 

 of maturity when plowed under. The table on next page shows the com- 

 position as determined by the average of a number of analyses, and gives 

 the fertilizing constituents in pounds per ton of dry matter for both tops 

 and roots in the crops indicated. 



In connection with the analyses as shown in this table, it should be 

 borne in mind that all of the mineral constituents come from the soil, 

 and that it is not possible to increase these by the growing of green manur- 



