8 Fertilizers 



SOUKCES OF NATURAL LOSS OF NITROGEN 



Of the essential constituent elements, nitrogen is, in 

 one sense, of the greatest importance ; first, because it is 

 the one that is more liable to escape than the others, and 

 secondly, because it is more expensive to supply arti- 

 ficially than are the minerals. It is the most elusive of 

 all the elements: to-day it may be applied to the soil, 

 to-morrow it may be carried in streams to the ocean. 

 It is also unstable which is not the least valuable of 

 its characteristics if properly understood: to-day it is 

 an element of the atmosphere, to-morrow it is a con- 

 stituent part of a growing plant, the next day the same 

 element may exist as an animal product, and the day 

 following it may be returned to the soil to feed the plant. 

 It is more liable to escape than any of the others, because 

 it is available as plant-food largely in proportion as it 

 changes to a nitrate, and after it assumes that form it is 

 seldom absorbed or fixed in the soil. Nitrogen in this 

 form remains freely movable, and the probability of loss 

 by leaching is increased in direct proportion to the lack 

 of preventive measures used, or the presence of those 

 conditions which favor leaching. The latter may be 

 classified as follows : First, the amount and time of the 

 rainfall ; secondly, the absorptive and retentive power of 

 the soil and subsoil, due to their mineral and physical 

 character; and thirdly, the amount of vegetable matter 

 (humus) acquired by the soil, which retards the passage 

 of water. While the amount and tune of rainfall can- 

 not be controlled, its effect upon our soils in this direction 

 can be largely governed if proper attention is given to 

 correcting the other conditions, and these may be largely 

 modified, if not entirely controlled. In the matter of the 



