FIXATION OF ATMOSPHERIC NITROGEN 



411 



known that all legumes, with the exception of lupines and serradella, 

 are stimulated in their growth by generous applications of lime. 



FIG. 135. These two pea plants were grown in clean quartz sand to which had 

 been added small quantities of all the necessary elements of plant food except 

 nitrogen. The conditions were exactly identical except that plant A was without 

 root nodules (see Fig. 136) and plant B had numerous nodules well developed (see 

 Fig. 137). (Mich. Exp. Station.} 



The top dressing of lawns with lime, marl or wood ashes encourages 

 the appearance of white clover; an adequate supply of lime makes 



