The Composition and Use of Fertilizers. 303 



Nitrogen. 



(a) Nitrogen is a gas and, in tliis form, cannot be used in fer- 

 tilizers. Therefore, whenever we speak of nitrogen in fertilizers, 

 we do not mean that nitrogen exists in them as simple nitrogen. 

 As previously stated, the nitrogen in fertilizers is always com- 

 bined with other elements and may be present in one or more 

 different forms: (1) in the form of nitrates, as nitrate of soda; 

 (2) in the form of ammonia compounds, as sulphate of ammonia; 

 and (3) in the form of organic matter, animal or vegetable, as 

 dried blood, meat, tobacco stems, etc. Chemical analysis fre- 

 quently does not ascertain and state in which form or forms the 

 nitrogen is present in a fertilizer. 



When, therefore, nitrogen is expressed in an analysis or guar- 

 antee simply as " nitrogen," it refers to the entire amount of 

 nitrogen present without regard to the particular form or forms 

 in which it is present. 



(6) Ammonia consists of nitrogen comhined with hydrogen. — A 

 pound of nitrogen will form more than a pound of ammonia, be- 

 cause the ammonia formed from a pound of nitrogen will con- 

 tain that pound of nitrogen plus the necessary amount of hydro- 

 gen added to form ammonia. The chemical relations of nitrogen 

 and ammonia are such that 14 pounds of nitrogen will unite with 

 exactly three pounds of hydrogen, and will, therefore, produce 

 just 17 pounds of ammonia; or one pound of nitrogen will make 

 1.214 pounds of ammonia. 



Manufacturers very commonly express the amount of nitrogen 

 in the equivalent of ammonia, probably for the reason that, ex- 

 pressed as ammonia, larger figures are obtained than would be, 

 if expressed as nitrogen; and the fertilizers appear to farmers 

 to contain more nitrogen. Farmers should hnow that "nitrogen " 

 and "ammonia" are not the same, thing, since one 'pound of am- 

 monia contains only about eight-tenths of a pound of nitrogen. 



(c) Nitrogen equal (or equivalent) to Ammonia is a form of 

 expression which simply means that the nitrogen is stated not as 

 nitrogen but as ammonia. 



It would be better on every account if all guarantees stated 

 simply nitrogen and never mentioned ammonia at all. As a 

 matter of fact, compounds of ammonia are quite uncommon in 

 commercial fertilizers, because nitrogen in this form is generally 

 the most expenshe and, therefore, least used. Strictly speaking, 

 the term ammonia should never be used except when sulphate of 

 ammonia or some similar compound is present in the fertilizer. 



