250 AGRICULTURAL EXPERIMENT STATION. [Jan. 



not express their respective agricultural value, i. e., their 

 crop-producing value ; for the higher or lower market price 

 of different brands of fertilizers does not necessarily stand 

 in a direct relation to their particular fitness, without any 

 reference to the particular condition of the soil to lie treated 

 and the special wants of the crops to be raised by their 

 assistance. 



To select judiciously from among the various lirands 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 in question actually 

 contains the guaranteed quantities and qualities of essential 

 articles of plant food at a reasonable cost, and that it con- 

 tains them in such form and such proportions as will best 

 meet existing circumstances and special wants. In some 

 cases it may l)e 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 a])ove-stated 

 considerations. 



To assist farmers not yet fiimiliar with the current mode 

 of determinino; the commercial value of manurial substances 

 offered for sale in our markets, some of the essential con- 

 siderations, which serve as a basis for their commercial 

 valuation, are once more stated within a few su])sequent 

 pages. 



The hitherto customary valuation of manurial suljstances 

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

 izing elements specified by analysis. The money value of 

 the hiiiher j^rades of agricultural chemicals and of the higher- 

 jjriced compound fertilizers depends, in the majority of 

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

 three essential articles of plant food, i. c, phosphoric acid, 

 nitrogen and potash, which they contiiin. To ascertain by 

 this mode of valuation the approximate market ^'alue of a 

 fertilizer (i. e., the money worth of its essential fertilizing 

 ingredients), we multiply the pounds per ton of nitrogen, 

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

 adopted with reference to the various forms of i)hosphoric 



