56 CLOVERS 



lations thus tried under the supervision of the 

 United States Department of Agriculture have 

 proved quite successful. 



Where any legume is extensively grown surround- 

 ing soils come to be inoculated through the agency of 

 winds and water. The increase brought to the yield 

 of plants on various soils runs all the way from 

 a slight gain to looo-fold. And when soil is once 

 inoculated it remains so for a long time, even though 

 the proper legume should not be grown again on the 

 same soil. 



The amount of nitrogen that may thus be brought 

 to many soils by growing clover and other legumes 

 upon them is only hedged in practically by the 

 nature of the rotation fixed upon. An acre of clo- 

 ver when matured will sometimes add 200 to 300 

 pounds of nitrogen to the soil under favorable con- 

 ditions. Where the soil contains the requisite bac- 

 teria, the young plants begin to form tubercles when 

 but a few weeks old, and continue to do so while the 

 plant is active until mature. That the plants use 

 much of the nitrogen while growing would seem 

 to be clear, from the fact that toward the close of 

 the growing season the tubercles become more or 

 less broken down and shrunken. 



