Chemical Analyses of Fertilizers 179 



tion may result in a very great increase in the value of 

 the crop. The character or form of the materials used in 

 a mixture, as well as their suitability for the crop must, 

 therefore, be carefully considered in the purchase of fer- 

 tilizers. Slow-acting materials cannot be expected to give 

 profitable returns, particularly upon quick-growing crops, 

 nor expensive materials such profitable returns, when used 

 for crops of relatively low value, as for crops of relatively 

 high value. 



THE COMMERCIAL VALUE OF A FERTILIZER 



This agricultural value, however, is separate and 

 distinct from what is termed "commercial value/' or 

 cost in market. This value is determined by market 

 and trade conditions, as the cost of production of the 

 crude materials and the cost of their manufacture and 

 sale. Since there is no strict relation between agricul- 

 tural and commercial or market value of a fertilizer con- 

 stituent, it frequently happens that an element in its 

 most available form, and under ordinary conditions of 

 high agricultural value, costs less in market than the same 

 element in less available forms and of a lower agricultural 

 value. The cost of production in the one case is lower 

 than in the other, though the returns in the field are far 

 superior. 



It is manifestly impossible to fix an agricultural value 

 for any of the constituents that will be true under the 

 varying conditions of soil, crop and season, and method of 

 use, though the relative value of the different forms under 

 uniform conditions of use may be fairly indicated, and the 

 analysis is the guide as to their form. The commercial 

 value of the different constituents in their various forms 



