180 STATE BOARD OF AGRICULTURE. 



are used for the most part. The concentrated manures are nourishment 

 and in a form fitted for immediate use. But if these materials are in a 

 form unavailable by the plant, or deficient in supply, then all the other 

 elements of fertility will be correspondingly limited in action. Often 

 the largest benefit secured by the use of these fertilizers is by their 

 setting other substances at work in the soil which would otherwise 

 remain inactive. 



HOW COMMERCIAL FERTILIZERS ARE COLLECTED AND ANALYZED. 



The law in force in this State on the inspection of commercial fer- 

 tilizers requires that samples of fertilizers retailing for more than ten 

 dollars a ton shall be gathered in the open market and analyzed under 

 the direction of the State Board of Agriculture at least once a year. 

 A representative of the chemical department visits various parts of the 

 State and collects samples of all fertilizers he finds on sale. When a 

 dealer has several packages of the same fertilizer a handful is taken 

 from each bag, the whole well mixed, and then a pound taken for an 

 average sample for analysis. On a card is entered the name and ad- 

 dress of the manufacturers, the trade name of the fertilizer, the name 

 and address of the dealer and date of collecting. This card is inclosed 

 with the specimen in a tight can and brought to the laboratory for analy- 

 sis. When all the speciments are collected, a careful analysis is made 

 of each fertilizer to determine the amount of nitrogen in the form of a 

 salt of ammonia, a nitrate or organic nitrogen; the amount of phos- 

 phoric acid, which is soluble in water, or in a solution of citrate of 

 ammonia (reverted), and insoluble or mineral phosphate; and the potash 

 soluble in water. In the Bulletin the results of anlysis are entered in 

 a horizontal line, and in a parallel line the percentage amounts claimed 

 of the same material by the manufacturer, thus admitting of ready 

 comparison of the "claimed" and "found" composition. 



TERMS EXPLAINED. 



In the table giving the results of analysis of commercial fertilizers 

 there are certain terms used which require explanation: "Available 

 nitrogen, estimated as ammonia;" under "Phosphoric acid" the terms 

 "Available P 2 5 ;" "Insoluble P 2 5 ;" Total P 2 6 " aud "Potash soluble in 

 water, estimated as K 2 O." 



Nitrogen may exist in available form either as a salt of ammonia, a 

 nitrate, or in organic material such as dried blood, and be equally val- 

 uable in these several forms. But for ease of comparison in different 

 manures chemists estimate it as if all these forms of nitrogen existed 

 in the form of ammonia. Chemists estimate the compounds of phos- 

 phorus in manures as anhydrous phosphoric acid, P 2 O a ; that is, phos- 

 phoric acid deprived of water; when this anhydride combines with 

 water, the acid is formed. Thus if three molecules of water are added 

 to one of P, O- two molecules of phosphoric acid are formed 3BD,0 + 

 P 2 5 — 2 H 8 POi — phosphoric acid. The P 2 O s in separate form 

 does not exist in any soil, but this expression is chosen because the 

 amount of this combination of phosphorus is easily indicated, without 

 considering what material the acid may be combined with. "Available 

 P., O ft " signifies the per cent of the acid in a form directly usable by the 

 plant: "Insoluble P., 0-„" the per cent of acid in the condition of 



