39 



supposed to be readily available to growing plants. The term "inac- 

 tive organic" nitrogen designates that portion of the total organic 

 nitrogen which would be less available to growing plants than that 

 which is indicated as active. 



In the phosphoric acid column the insoluble phosphoric acid is 

 that part of the total phosphoric acid insoluble in water or a neutral 

 solution of citrate of ammonia. The reverted phosphoric acid is 

 that portion dissolved by a neutral solution of citrate of ammonia 

 (specific gravity 1.09) by treating two grams of the fertilizer, pre- 

 viously washed with water, with 100 c. c. of the citrate solution 

 one-half hour at 65°C. It is supposed to represent that part of the 

 phosphoric acid insoluble in water but soluble in soil and root acids 

 — it represents the difference between the total and the sum of the 

 soluble and insoluble phosphoric acids. The available phosphoric 

 acid colimm represents the sum of the soluble and reverted phos- 

 phoric acid. 



The potash column shows the percent of potash soluble in water; 

 results published without an asterisk (*) or dagger (f) indicate 

 that the potash is present as chloride or that sufficient chlorine is 

 present in the fertilizer to unite with all of the potash. Footnotes 

 indicate the amount of potash present as sulfate and carbonate. 



The guarantee columns show the minimimi percentage of nitro- 

 gen, total and available phosphoric acid, and potash guaranteed 

 by the manufacturer to be present. 



