No. 7. DEPARTMENT OF AGRICULTURE. 673 



FERTILIZER ANALYSES AUGUST 1, TO DECEMBER 31, 1906. 



Since August 1, 1906 there have been received from authorized 

 sampling agents eleven hundred and ten fertilizer samples, of which 

 four hundred and twenty-two v>'ere subject to analysis, the re- 

 mainder being rejected either because they represented brands 

 analyzed last season, or because they were regarded as not certainly 

 representative of the brand whose name they bore. When two or 

 more samples representing the same brand were received equal por- 

 tions from the several samples were united and the composite sam- 

 ple was subject to analysis. 



The samples analyzed group themselves as follows, 266 complete 

 fertilizers, furnishing phosphoric acid, potash and nitrogen; 7 dis- 

 solved bones furnishing phosphoric acid and nitrogen; 71 rock-and- 

 potash fertilizers, furnishing phosphoric acid and potash; 43 acidu- 

 lated rock phosphates, funishing phosphoric acid only; 34 ground 

 bones, furnishing phosphoric acid and nitrogen, and one miscellane- 

 ous sample, which group includes substances not properly classified 

 under the foregoing heads. 



The determinations to which a complete fertilizer is subjected are 

 as follows: (1) Moisture, useful for the comparison of analyses, for 

 indication of dry condition and fitness for drilling, and also of the 

 conditions under which the fertilizer was kept in the warehouse. (2) 

 Phosphoric acid — total, that portion soluble in water, andof the 

 residue, that portion not soluble in warm ammonia citrate solution 

 (a solution supposed to represent the action of plant roots upon 

 the fertilizer), which is assumed to have little immediate food value. 

 By difference, it is easy to compute the so-called "reverted" acid, 

 which is the portion insoluble in water but soluble in the citrate. 

 The sum of the soluble and reverted is commonly called the "avail- 

 able" phosphoric acid. (3) Potash soluble in water — most of that 

 present in green sand marl and crushed minerals, and even some of 

 that present in vegetable materials such as cotton-seed meal, not 

 being included because insoluble in water even after long boiling. 

 (4) Nitrogen — This element is determined by a method which simply 

 accounts for all present, without distinguishing between the quanti- 

 ties present in the several forms of ammonium salts, nitrates or or- 

 ganic matter. (.5) Chlorin; this determination is made to afford a 

 basis for estimating the proportion of the potash that is present as 

 chlorid or muriate, the cheaper source. The computation is made 

 on the assumption that the chlorin present, unless in excess, has 

 been int'"oduced in the form of muriate of potash; but doubtless 

 there ^re occasional oxeej)tions to this rule. One part of chlorin 

 combines with 1.326 parts of potash to form the pure muriate; know- 

 ing the chlorin, it is, therefore, easy to compute the potash equiva- 

 lent thereto. (7) In the case of ground bone, the state of sub-divi- 

 sion is determined by sifting through accurately made sieves; the 

 cost of preparation and especially the promptness of action of bone 



43—7—1906. 



