154 Fertilizers 



STANDARD HIGH-GRADE MATERIALS 



Nitrate of soda, sulfate of ammonia and dried blood 

 are, for example, standard or high-grade nitrogenous 

 materials, and belong to the first group. They are " stand- 

 ard" because they do not vary widely in their composi- 

 tion. A definite quantity can be depended upon to fur- 

 nish not only practically the same amount of the specific 

 constituent, but to furnish it in a distinct and definite 

 form, which is identical, from whatever source derived. 

 For example, commercial nitrate of soda does not vary 

 materially in its composition, and the nitrogen in it is 

 always in the form of a nitrate. The same is true of sul- 

 fate of ammonia. One ton will furnish practically as 

 much nitrogen as any other ton, and it is always in the 

 form of ammonia. It is also practically true of high- 

 grade dried blood. Each lot contains this specific form 

 of organic nitrogen, and will always decay at practi- 

 cally the same rate, if used under the same conditions. 

 They are also high-grade products because they are richer 

 in the constituent element, nitrogen, than any other, 

 and because this element is immediately or quickly avail- 

 able. 



The South Carolina, Florida and Tennessee rock phos- 

 phates differ from the nitrogenous materials mentioned, 

 inasmuch as, in their raw state, they are not directly 

 useful as fertilizers, they are not sources of available 

 phosphoric acid. Hence the standard supplies of phos- 

 phoric acid are derived from these materials after they 

 are manufactured into superphosphates. The various 

 kinds of these may be regarded as high-grade in the sense 

 that they always possess a high content of available phos- 

 phoric acid. They are standard, too, not only because 



