316 PRINCIPLES OF AGRICULTURAL CHEMISTRY 



(b) The Unit Method. A unit is i per cent., and i per cent, 

 of a ton is 20 pounds. Hence 20 times the value of a pound gives 

 the value of a unit. To calculate the valuation, multiply per- 

 centage by value per unit. With nitrogen at 20 cents a pound, a 

 unit costs $4.00. With potash at 6 cents, the unit costs $1.20. 

 Using the example given above: 



8.0 X $1.20 = $9.60 



1.65 X 4-0 - 2.60 



2.0 X 1-20 = 2.40 



Valuation per ton $21.60 



The Meaning of Commercial Valuation. The valuation of a 

 brand of fertilizer by the State Fertilizer Control does not repre- 

 sent its proper selling price at the point of consumption. Neither 

 should it be inferred that the ingredients in the brand in question 

 have of necessity the commercial value indicated. It may be greater 

 or less than is shown. The valuation system is based on the as- 

 sumption that all brands compared are solely of high grade in- 

 gredients, an assumption which may be erroneous. "Valuations" 

 should not be construed as showing the commercial worth of a 

 given fertilizer, but the retail trade value at the seaboard, of 

 amounts of nitrogen, phosphoric acid, and potash, equal to those 

 contained in a ton of the brand in question, in unmixed, standard 

 raw materials of good quality. 



Valuations thus construed, while not infallible, are helpful : 



(a) To show whether a given fertilizer is worth its cost from 

 the commercial standpoint. 



(b) As a common basis on which to compare the commercial 

 value of different brands, enabling buyers to note whether prices 

 asked are warranted by values contained, and aiding buyers to 

 secure the most value for the least money. 



Agricultural Value. The agricultural value of a fertilizer is 

 measured by the value of the increased crop produced by its use. 

 It is variable, depending upon the availability of the constituent, 

 the value of the crop, the needs of the soil, weather conditions, 

 etc. For example, the agricultural value of a pound of water- 

 soluble phosphoric acid is likely to be greater than that of 



