CLOVER AND OTHER LEGUMES 



209 



and thus makes the air fit for animals to breathe. Farm 

 crops cannot use this "free" nitrogen that is in the air. 



Nitrogen - gathering bacteria. Little plant - like 

 germs, called bacteria, live in the soil, and these feed 

 upon this free nitrogen in the air. These germs fasten 

 themselves to the roots of the legumes, such as clover 

 and cowpeas, and build 

 little colonies that are 

 t-alled tubercles. These 

 tubercles are about as 

 large as pinheads, and' 

 may easily be seen on 

 the roots of clover, 

 beans, and peas. The 

 interesting thing about 

 these germs is that they 

 do not seem to grow 

 without the clover, and 

 the clover does not 

 thrive without the 

 germs. In most soils 

 the germs will find the 

 clover, but occasionally soils from old clover fields have 

 to be sprinkled over the new clover fields in order for 

 the young clover to "catch." 



These germs found in the tubercles on the roots of 

 legumes, in feeding upon the nitrogen of the air, store 

 large quantities of the nitrogen in the plant and in the 

 soil about the plant. If this crop is plowed under, 

 additional nitrogen is added to the soil, and 



FIG. 59. TUBERCLES ON THE ROOTS 

 OF SOY BEANS 



