THE NEW EARTH 



steadily reducing the yield until, at last, the 

 soil was worn out and ruin stared him in the 

 face. Now it appears feasible for him to restore 

 his soil nitrogen simply by inoculation. 



In this connection it is of interest to note 

 that the Department of Agriculture in Wash- 

 ington has begun the work of sending out 

 bacteria for inoculating the soil direct. 



Certain plants bearing root-nodules, the 

 leguminous plants, have long been used as 

 green manure, the farmer plowing under the 

 green plants in order that the soil might be 

 enriched through the rich deposits of nitroge- 

 nous matter coming from the decaying roots, 

 and stored up by the bacteria from the nitro- 

 gen of the atmosphere. But in case the plants 

 have no nodules upon their roots, as in the 

 case of the soy bean in Kansas before inocula- 

 tion, such plants are of no more value for 

 plowing under as a green manure than any 

 other grain or grass. Curiously enough, it may 

 be noted in passing, the l>;.cteria of the differ- 

 ent legumes, as peas and clovers, are different, 

 the bacteria of one plant refusing to make its 

 home upon the roots of another, and vice 

 versa. 



40 



