82 FOOD FOR PLANTS 



cerned a soil without water is as useless as a motor 

 car without gasoline. 



The possibility of utilizing the legumes has been 

 known since the time of the Romans, although they 

 did not know it was nitrogen that was thus captured. 

 The potency of nitrogen in agriculture has been 

 known for years and has been studied especially 

 lately by leading agriculturists. 



The wide distribution of this element in nature is 

 remarkable. Its occurrence is universal. We may 

 fiy to the uttermost parts of the earth and it is still 

 with us. Throughout the world it remains substan- 

 tially in the same proportion to the oxygen of the air 

 although the atmosphere is supposed to have been 

 once all nitrogen. 



Nitrogen is found free not only in the atmosphere 

 but in certain mineral waters and in volcanic gases. 

 It is never absorbed by animals or plants from its 

 elementary state except through the agency of cer- 

 tain soil bacteria associated with leguminous plants, 

 and when these are located on favorable soils carry- 

 ing sufficient lime in proper form. 



The inactivity of elementary nitrogen is notable. 

 Its compounds, on the other hand, frequently have 

 pronounced and unusual properties, they being the 

 essential components of powerful drugs, of brilliant 

 dyestuffs and of high explosives. 



In its combined form it is widely and universally 

 distributed in the animal and vegetable kingdoms in 

 albuminoid or proteid bodies, like the casein of milk 

 or the gluten of wheat. Vast quantities of combined 

 Nitrogen occur in Chile in mineral deposits; it is 

 found combined in all arable soils; also in coal. In 



