358 STATE BOARD OF AGRICULTURE 



SCHEDULE OF COMMERCIAL PRICES. 



The following prices per pound for fertilizing materials may be used in estimat- 

 ing the commercial value: 



Per pound. 



Nitrogen in nitrates 13 cents 



Nitrogen in ammonia salts 1-i cents 



Organic nitrogen in meat, blood, etc 14 cents 



Organic nitrogen in fine bone and tanliage 13% cents 



Organic nitrogen in medium bone and tankage 10 cents 



Organic nitrogen in course bone and tankage 8 cents 



Phosphoric acid, available 4% cents 



Phosphoric acid, insoluble, in fine bone and tankage 4 cents 



Phosphoric acid, insoluble, medium bone and tankage.... 3^3 cents 



Potash as muriate 4% cents 



Potash as sulphate and in wood ashes 5 cents 



In the table of analysis the results are given as so many parts in a hundred. 

 Since there are 20 times 100 pounds in a ton, if we multiply the value of one 

 pound by 20 we find the value of one per cent of any material in a ton. We 

 may thus construct a table for estimating the value of any materials found in 

 the results of analysis. One per cent means 20 pounds in a ton, and if the mate- 

 rial is worth 5 cents a pound, then each per cent equals $1.00 for a ton. 



COMMERCIAL VALUE AND AGRICULTURAL VALUE. 



The commercial value and the agricultural value are not identical. The com- 

 mercial value merely represents the cost of the material to make the fertilizer, 

 if any one should attempt to make his own. The agricultural value of the benefit 

 from the use of such fertilizer will depend upon a variety of conditions, such as 

 the kind of soil, the crop, the season, the tillage, time of application, etc., etc. • Let 

 no one suppose that the estimate of the commercial value is a guarantee of a cor- 

 responding profit by its use on the farm. It may serve, however, as a basis of 

 comparison between different brauds of fertilizers. The reliable test of the value 

 is determined, by its use on a given soil and crop— worth more than all theoretical 

 discussions and' deductions. Yet there are certain general considerations which go 

 to show the probable benefit of any fertilizing element when used on a certain kind 

 of soil and crop, which will be of some benefit in selecting a fertilizer. 



TERMS EXPLAINED. 



In the table giving the results of analysis of commercial fertilizers there are 

 certain terms used whicli require expiananion: "Available nitrogen, estimated as 

 ammonia;" under "Phosphoric acid" the terms "'Available Po O5;" "Insoluble Po Os;" 

 "Total P2 O5" and "Potash soluble in water, estimated as Ko 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 valuable in these several 

 forms. Btit for ease of comparison in different manures chemists estimate it as 

 if all these forms of nitrogen existed in the form of ammonia. Lhemists esti- 

 mate the compounds of ])hospltorus in manures as anhydrous pliosphoric acid, Po O5; 

 that is, phosphoric 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 

 P2 O5 two molecules of phosphoric acid are formed 3HoO -\- P2 O5 = 2 H3 PO4 = 

 phosphoric acid. The Po O5 in separate form does not exist in any soil, but 

 this expression is chosen because the amount of this combination of phosphoi'us 

 is easily indicated, without considering what material the acid may be combined 

 with. "Available Pj Oj" signifies the per cent of the acid in a form directly usable 

 by the plant: "Insoluble Po O5,'" the per cent of ac'd in the condition of phosphate 

 rock. Bv adding together the "Available" and "Insoluble" we get the "Total 

 P2O5." 



The "Potash soluble in water, estimated as K2O, is the soluble potash salt esti- 

 mated only as regards the oxide of potassium=K20=oxide of kalium or potassium. 



