86 MAINE AGRICULTURAL e;xpe;rimi;nt station. 191 1. 



Potash as high grade sulphate and in forms free from 



muriate (chloride) 5 



as muriate 4^ 



in cottonseed meal and castor pomace. 5 



RUIvKS FOR CALCULATING VALUATION OF FLRTILIZLRS. 



The commercial valuation will be accurate enough as a means 

 of comparison if the following rule is adopted : 



Multiply 4.0 by the percentage of nitrogen. 



Multiply 0.8 by the percentage of available phosphoric acid. 



Multiply 0.4 by the percentage of insoluble phosphoric acid. 



Multiply i.o by the percentage of potash. 



The sum of these 4 products will be the commercial valua- 

 tion per ton on the basis taken. 



Illustration. The table of analyses shows a certain fertilizer 

 to have the following composition : Nitrogen 3.30 per cent ; 

 Available phosphoric acid 8.00 per cent; Insoluble phosphoric 

 acid 1. 00 per cent; Potash 6.00 per cent. The valuation in this 

 case will be computed thus : 



Nitrogen, 4-0 X 3-30, $13 20 



Available phosphoric acid, 0.8 X 8.00, 6 40 



Insoluble phosphoric acid, 0.4 X i-OO, 40 



Potash, ■ 1.0 X 6.00, - 6 00 



$26 GO 



Since this rule assumes all the nitrogen to be organic and all 

 the potash to be in the form of the sulphate, it is evident that the 

 valuations thus calculated must not be taken as the only guide in 

 the choice of a fertilizer. In every case the farmer should con- 

 sider the needs of his soil before he begins to consider the cost. 

 In many instances a little careful experimenting will show him 

 that materials containing either nitrogen, potash, or phosphoric 

 acid alone will serve his purpose as fully as a "complete fer- 

 tilizer," in which he must pay for all three constituents, whether 

 needed or not. 



