Methods of Use of Fertilizers 201 



though possessing marked distinguishing characteristics. 

 Of the grasses, nearly all species are perennial, though their 

 length of life depends upon the method of cropping and 

 upon the character of the soil. They send their fibrous 

 roots into the surface soil in the same manner as the cereals, 

 though they differ from them in forming a set of buds 

 which become active in the late summer and develop new 

 roots and shoots. They resemble the cereals in their 

 power of acquiring mineral food, and are even more bene- 

 fited by the application of nitrogen, since the chief object 

 in their use is to obtain the nitrogenous substances con- 

 tained in leaf and stem in the form of pasture, forage or 

 hay, rather than the matured grain. Hence, nitrogen, 

 which promotes this form of growth, is an important 

 constituent, and under any conditions there should be a 

 liberal supply provided. 



The clovers, on the other hand, are not perennial, with 

 the partial exception of "white" or "Dutch" clover, and 

 with this exception they all possess a taproot, which pene- 

 trates downward, and as it descends, throws out fibrous 

 roots into the various layers of soil. They are capable 

 of readily acquiring their mineral food, both because 

 of their large root systems and because of the charac- 

 ter of the roots. They, however, differ in one very 

 important particular from the cereals and grasses, 

 in that under proper conditions, as already pointed 

 out (p. 129), they are capable of acquiring their ni- 

 trogen from the air. Thus with liberal dressing of 

 only phosphoric acid and potash, maximum crops may 

 be secured. They are "nitrogen gatherers," and the 

 tendency of their growth is to improve the soil for the 

 nitrogen consumers, or for those that obtain their ni- 

 trogen only from soil sources. 



