SOILS AND FERTILIZERS 115 



ganisms. At the cost of a few cents a bushel the seeds 

 of peas, beans, clover, alfalfa, or any other legumes 

 may be inoculated with these bacteria, thus making 

 it possible to secure good crops on soils poorly supplied 

 with nitrogen, and at the same time leave a large 

 amount of the element fixed in the soil available to 

 wheat, corn, potatoes, or any other crop that may 

 follow the legumes. The bacteria are helped to live 

 and multiply by their host plant, the host in turn 

 is supplied with nitrogenous food by these bacteria, 

 and the host, upon dying, leaves its decaying roots, 

 leaves, and stems to supply stored-up nitrogen to 

 succeeding crops or to neighboring plants which may 

 outlive the legume and feed upon its disorganized 

 parts. 1 



Experiments are being conducted at different ex- 

 periment stations to ascertain whether nitrogen fixa- 

 tion can be secured without legumes, but while there 

 has been a degree of success attained, the work is yet 

 in the experimental stage. 



Note. If legumes are grown in soil well supplied with compounds 

 of nitrogen, as nitrates, tubercles will not grow on the roots. Bacteria 

 will fix nitrogen from the air when the plant needs it for its growth. 

 When the soil is poorly supplied with compounds of nitrogen, tubercles 

 on the roots of the legumes grow in large numbers and often in large 

 clusters. 



Denitrification. While the work of certain bacteria 

 through nitrification is beneficent to the plant world, 

 there are others of these microscopic plants that ac- 

 complish the opposite result, in that they act upon 

 the nitrates, breaking up these compounds and restor- 



1 See Farmers' Bulletin, 315; Progress in Legume Inoculation. 



