DISTRIBUTION OF THE CLOVERS, 



CHAPTER II. 



If the statement in the last paragraph of the previous 

 chapter be true that "the cultivation of some variety of the Le- 

 guminosa is essential to any great improvement, either in 

 grain production, the production of livestock or the conserva- 

 tion of the fertility of the soil," then the distribution of the 

 legumes, and especially of the clovers, becomes a question 

 alike of great scientific and practical importance. A crop 

 that can not only supply itself with nitrogen, to a great ex- 

 tent independently of the nitrogen of the soil, but, by the de- 

 cay of its roots and haulm supply other crops with nitrogen,. 

 is the very keystone of the arch of successful agriculture where- 

 ever its cultivation is possible. 



The importance of the subject is greatly enhanced when 

 we take into consideration the relation it sustains to the fer- 

 tility of the soil, to growing crops and to the structure of all 

 animals. Nitrogen, while the most costly and an absolutely 

 essential element in soil fertility, in plant growth and in ani- 

 mal life, is one of the most abundant elements in all nature. 

 It constitutes about four-fifths of the atmosphere, where it 

 seems to be used merely to dilute the oxygen. It enters 

 into no chemical combinations with it, but co-exists simply 

 as a mixture, like sand in sugar. The process by which the 

 free nitrogen of the atmosphere is transformed into the ni- 

 trogenous compounds of the soil has long been a puzzle to 

 scientists, a puzzle all the more complicated and difficult of 

 solution because it has been held until quite recently by all 

 scientists and investigators that plants can not appropriate 

 free nitrogen from the atmosphere. It is a striking fact, how- 

 ever, that all the sources from which either the nitrogen of 



