230 AGRICULTURAL EXPERIMENT STATION. [Jan. 



any reference to the particular condition of the soil to be 

 treated, and the special wants of the crops to be raised by 

 their assistance. To select judiciously, from among the 

 various brands of fertilizers offered for patronage, requires, 

 in the main, two kinds of information; namely, we ought 

 to feel confident that the particular brand of fertilizer m 

 question actually contains the guaranteed quantities and 

 qualities of essential articles of plant food at a reasonable 

 cost, and that it contains them in such form and such pro- 

 portions as will best meet existing circumstances and special 

 wants. In some cases it may be mainly either phosphoric 

 acid or nitrogen or potash ; in others, two of them ; and in 

 others again, all three. 



A remunerative use of commercial fertilizers can only 

 be secured by attending carefully to the above-stated consid- 

 erations. 



To assist farmers not yet familiar with the current mode 

 of determining the commercial value of manurial sub- 

 stances offered for sale in our markets, some of the essen- 

 tial considerations, which serve as a basis for their 

 commercial valuation, are once more stated within a few 

 subsequent pages. 



The hitherto customary valuation of manurial substances 

 is based on the average trade value of the essential fertil- 

 izing elements specified by analysis. The money value of 

 the higher grades of agricultural chemicals, and of the 

 higher-priced compound fertilizers, depends in the majority 

 of cases on the amount and the particular form of two or 

 three essential articles of plant food — /.^., phosphoric acid, 

 nitrogen and potash — which they contain. To ascertain, 

 by this mode of valuation, the approximate market value 

 of a fertilizer (i.e., the money worth of its essential fertil- 

 izing ingredients) , we multipl}' the pounds per ton ot nitro- 

 gen, etc., by the trade value per pound ; the same course is 

 adopted with reference to the various forms of phosphoric 

 acid and of potassium oxide. We thus get the values per 

 ton of the several ingredients, and, adding them together, 

 we obtain the total valuation per ton in case of cash pay- 

 ments at points of general distribution. 



