INSPECTION OF COMMERCIAL FERTILIZERS 11 



the guarantee of nitrogen, available phosphoric acid and potash in mixed com- 

 mercial fertilizers be stated only in whole numbers. 



During the past year the fertilizer manufacturers, in conference with agron- 

 omists and control officials of New England and Middle Atlantic States, have 

 agreed to adopt, beginning with January 1, 1932, certain recommendations 

 that should eventually simplify some of the manufacturer's problems and 

 constitute a valuable educational feature in the selection and use of commerical 

 fertilizer mixtures. 



Beginning with January 1, fertilizer trade names will include the fertilizer 

 grade, which is the minimum plant food guarantee expressed in whole numbers 

 and in the order and terms of nitrogen, available phosphoric acid and water 

 soluble potash. This will be accompanied by a simple statement of guarantee 

 and read somewhat as follows: 



100 lbs. Net 



Good Luck 



5-8-7 

 For Potatoes 



Guaranteed Analysis: 



Nitrogen 5 



Available phosphoric acid 8 



Water soluble potash 7 



(Manufacturer's name and address) 



After January 1, the first figure in expressing fertilizer grade will refer to 

 nitrogen and not ammonia as in the past. This means that a 5-8-7 grade will 

 carry 5 per cent nitrogen in place of 4.11 per cent as heretofore. It is believed 

 that in most instances this 22 per cent increase in the nitrogen content of 

 fertiUzer mixtures will prove through increased yields to be good economy. 



For the purpose of reference, it may be recorded that 1 per cent ammonia 

 represents only .82 per cent nitrogen, and that 1 per cent nitrogen represents 

 1.22 per cent ammonia. 



F^iture guarantees will be much simplified by the omission of ammonia 

 equivalent, fractional analyses, and total, water-soluble and citrate-insoluble 

 phosphoric acid. 



The omission of the water-soluble phosphoric acid from the guarantee was 

 made for the purpose of simplifying the statement of analysis. It was formerly 

 believed that a mixed commercial fertilizer with a high percentage of water- 

 soluble phosphoric acid was superior to one with a high percentage of reverted 

 or citrate-soluble phosphoric acid and a correspondingly low percentage of 

 water-soluble form. This has not proved to be the case, however, and it seems 

 no longer necessary to make this distinction. 



Bone base fertilizer mixtures, containing all of their phosphoric acid in form 

 of undissolved bone, are to carry a guarantee of total phosphoric acid ac- 

 companied by a statement that all the phosphoric acid is derived from un- 

 dissolved bone, and the statement of grade may for the present be omitted. 

 Upon the adoption by the Association of Official Agricultural Chemists of a 

 modified method of determining available phosphoric acid in ammoniated 

 superphosphates made by using either anhydrous or liquid ammonia as the 

 source of nitrogen or in mixtures containing this product, it is believed that 

 the available phosphoric acid in bone base mixtures may be readily determined 

 by the same procedure. Statement of grade may then apply to such fertilizers 

 and the statement of total phosphoric acid may be omitted from the guarantee. 



