FERTILIZER PRACTICE 561 



to a large extent on the additional charges already listed. 

 Thus, a fertilizer evaluated at $22 a ton on the New York 

 market may cost the farmer $35, or even $45, after having 

 passed through the hands of the manufacturer and the 

 retail merchant. This commercial evaluation, however, 

 must not be confused with the agricultural evaluation, 

 which is the value of the increased crop produced by the 

 application of the fertilizer. It is evident that the agri- 

 cultural value will vary with the soil, the crop, or the 

 season, and may be above or below the total cost accord- 

 ing to circumstances. In good fertilizer practice, the 

 excess of the agricultural value over the total cost of the 

 fertilizer, all costs incidental with the growing, harvest- 

 ing, and marketing of the increase being first deducted, 

 should be sufficient to give a handsome profit on the 

 investment. 



473. The buying of mixed goods. — The successful 

 buying of mixed fertilizers on the retail market depends 

 on two things : (1) the selection of a suitable composi- 

 tion, with carriers of known value ; and (2) the purchase 

 of high-grade goods. The farmer who observes these 

 two points will have at least purchased successfully. 

 Whether he obtains a profit from the use of the fertilizer 

 depends on the balancing of a number of factors more or 

 less variable from season to season. 



The selection of a suitable fertilizer, as to carriers and 

 composition for any particular crop or soil, entails first 

 of all a study of the guarantee. Should the guarantee 

 be such as that already cited, a large amount of informa- 

 tion is at hand concerning the forms of the carriers and 

 the availability of the important constituents. This 

 knowledge, properly correlated with the probable needs 

 of the crop and the soil, will determine whether that 

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