No. 7. DEPARTMiENT OF AGRICULTURE. 669 



FERTILIZER ANALYSES JANUARY 1, TO AUGUST 1, 1906. 



Since January 1, 1906, there have been received from, authorized 

 sampling agents twelve hundred and fifty-three fertilizer samples, of 

 which six hundred and five were subject to analysis, the remainder 

 being rejected either because they represented brands analyzed last 

 season, or because they were regarded as not certainly representa- 

 tive of the brand whose name they bore. When two or more samples 

 representing the same brand were received equal portions from the 

 several samples were united and the composite sample was subject- 

 ed to analysis. 



The samples analyzed group themselves as follows, 285 complete 

 fertilizers, furnishing phosphoric acid, potash and nitrogen; 6 dis- 

 solved bones furnishing phosphoric acid and nitrogen; 74 rock-and 

 potash fertilizers, furnishing phosphoric acid and potash; 49 acidu- 

 lated rock phosphates, furnishing phosphoric acid only; 35 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, and of 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, r^ot 

 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 of muriate, the cheaper source. The computation is made 

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

 been introduced in the form of muriate of potash; but doubtless 

 there are occasional exceptions to this rule. One part of chlorin 

 combines with 1,320 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 

 in the soil depends very largely on the fineness of its particles the 

 finer being much more quickly useful to the plant. 



