92 



NITROGEN. 



Nitrogen is the most expensive of the three essential fertilizing ele- 

 ments. It exists in three distinct forms, viz., as organic matter, as 

 ammonia, and as nitrate. 



Organic nitrogen exist6 in combination with other elements either 

 as vegetable or animal matter. In fact all plants.and animals contain 

 nitrogen in this form, and the relative value of the various substances 

 as sources of nitrogen depends upon their con! ent of it and upon the 

 character of the substance and its treatment. All materials containing 

 organic nitrogen are valuable in proportion to their rapidity of decay 

 or change, because decay and change of form must take place before the 

 nitrogen can serve as food. In some cases the decay is longer delayed 

 than in others. The material may be hard and dense, or it may have 

 been treated for the express purpose of preventing decay, or it may be 

 associated with other substances that resist the agents which effect 

 decay. Thus organic nitrogen differs in availability not only according 

 to the kind of material which supplies it, but upon the treatment it 

 receives. 



The most abundant supplies of nitrogen occur in organic forms. The 

 most valuable sources of organic nitrogen, from the standpoints of uni- 

 formity in composition, richness in the constituent, and availability, are 

 dried blood, dried meat, or azotine, and concentrated tankage, which 

 are produced in large quantities in slaughterhouses and rendering 

 establishments ; dried fish, refuse from fish-oil and canning establish- 

 ments; and cotton-seed meal, the residue of the cotton seed after the 

 oil has been extracted. These vary somewhat in composition, but 

 within comparatively narrow limits (see table, p. lOo). They are all 

 rich in nitrogen, and decay rapidly when the conditions are favourable, 

 and are very useful in cases were rapid and continuous feeding of the 

 plant with nitrogen is desirable. 



These products, while valued principally as sources of nitrogen, also 

 furnish more or less phosphoric acid, the dried blood and meat showing 

 the least and the fish the greatest amount. Other nitrogenous mate- 

 rials which are less desirable are leather meal, horn and hoof meaL 

 wool waste, felt waste, and similar products. These contain, as a rule, 

 a high content of nitrogen, but they are so very slow to decay that it is 

 doubtful whether their use in their original form is advisable when 

 forms of known value are available at reasonable prices. Where the 

 object is gradually to increase the fertility of the soil rather than to 

 6ecure immediate returns, they may become useful. Farmers fre- 

 quently have access to local supplies at a slight cost, the chief expense 

 being the labour of carting and distributing, in which case they are 

 worth considering. 



Nitrogen as ammonia exists in commercial manure products in the 

 form of sulphate of ammonia, chloride of ammonia, etc., and is more 

 readily available than organic forms. It is one of the first products 

 that results from the decay of organic substances. 



Nitrogen in the form of ammonia is obtained almost entirely from 

 sulphate of ammonia, which is one of the most concentrated materials 

 from which nitrogen is obtained for fertilizing purposes, the commercial 

 product containing on the average 20 per cent, of nitrogen. As already 

 indicated, ammonia is one of the first products in the decay of organic 



