TWENTY-THIRD CHAPTER. 



CLOVER AND OTHER PLANTS AS 

 MANURE CROPS. 



/^ LOVER, as hay crop, is one of the chief links in 

 the chain of farm crop rotation; And it is a 

 wonderful crop — somewhat of a paradox. Generally- 

 accepted as a "renovator of land," and a crop which 

 gives to it something like a "resting spell," it draws 

 more heavily on the supplies in the soil than any 

 other crop; for in two tons of clover hay (supposing 

 such to be a good yield on an acre of good soil, and 

 perhaps a fair equivalent of the thirty bushels of 

 wheat), we take from the one acre about 120 pounds 

 of nitrogen, ninety-three of potash and twenty- 

 seven of phosphoric acid. At the same time the 

 roots and stubs on the same area contain 175 pounds 

 of nitrogen and more than seventy pounds each of 

 potash and phosphoric acid, all of which probably 

 are a kind of reserve store, largely going to supply 

 the materials for the production of after-growth and 

 seed. The whole crop (top and root) has absorbed 

 an aggregate of 300 pounds nitrogen, 165 pounds of 

 potash and 100 pounds of phosphoric acid. Com- 



