MANURES. 269 



and the success with which this process is availed of for our 

 purposes depends almost entirely upon a proper selection of the 

 plant which is to be used. In America it has come to be an 

 established fact that, wherever clover will grow, it is, all things 

 considered, the best plant for our use ; but the same rules which 

 regulate its adoption and the extent to which we may avail our- 

 selves of its action, govern the cultivation of all other plants for 

 this purpose. Clover is a plant which is capable of germinating 

 and commencing its growth under circumstances of sterility which 

 would be unfavorable to almost all other farm crops. Often, 

 where nothing of value would grow, the application of a few 

 bushels of ground plaster to the acre will be sufficient to stimulate 

 this plant to an active vegetation. Its roots are exceedingly 

 strong, descend to a great depth into the soil, and have an 

 extraordinary power of absorbing matters which, to the roots of 

 other plants, would be entirely unavailable. Its foliage is abund- 

 ant and fleshy, and, under favorable circumstances, it absorbs ample 

 supplies from the atmosphere. It is asserted, though, perhaps, not 

 quite proven, that clover takes up the free nitrogen of the air. 

 Whether this is true or not, there seems little doubt that it either 

 avails itself of the small quantities of ammonia that come in con- 

 tact with its leaves, or that it has the peculiar power of extracting 

 ammonia from the soil which would not be yielded to most other 

 crops. Certain it is that both its upper part and its roots contain 

 much more nitrogen than would any other plant with which we 

 are acquainted, grown under similar circumstances. The mineral 

 food which it gets from the soil and subsoil — notably from the 

 latter — and the supplies from the atmosphere, are stored up, not 

 only in the stems and leaves, but, to a very hrgh extent, in the 

 roots also. And when the crop is turned under by the plow, or 

 even when the principal growth having been removed for hay, the 

 roots are killed by the plow, and mixed, as so much dead organic 

 matter, with the soil, their decomposition adds to it, in a readily 

 available form, all of those contents of root and stem bv which 

 the growth of future crops is to be benefited. And, in addition to 

 all this, the lower ends of the roots, below where they arc cut off 



