THE PURCHASE AND MIXING OF FERTILIZERS 203 



for a group of consumers to purchase the fertilizer ingredients 

 in car-load lots and do the mixing themselves. 



It must also be remembered that this is the commercial 

 value and not necessarily the agricultural value, which latter 

 is determined by the profits from its use, and will depend on 

 many factors. 



. 257. Home mixing of fertilizers. — There is a large margin 

 between the trade value of fertilizer ingredients and their 

 retail price as sold by the dealer. The cost of the raw ma- 

 terials often doubles in the process of mixing and retailing, 

 with the necessary transportation. It has been demon- 

 strated that the raw materials may be purchased from the 

 wholesale dealer and mixed by the consumer at a consider- 

 ably lower cost than if purchased mixed from the retail dealer, 

 and that the results are fully as satisfactory. 



Other advantages from home mixing are that it permits 

 the farmer to use exactly the proportion of the several con- 

 stituents that he desires, and that it makes unnecessary 

 the handling of a large amount of inert materials frequently 

 contained in mixed fertilizers. It is thus possible for him 

 to ascertain, by field tests, the best proportions of the various 

 fertilizer constituents to use on his own land for each of the 

 crops he is growing. This knowledge makes it possible to 

 decrease greatly the expenditure for fertilizers. 



258. Fertilizers that should not be mixed. — Because 

 fertilizers consist of chemicals, some of which react on each 

 other to form compounds different from those in the original 

 substances, it is unwise to mix certain of these carriers. 

 The result may be to convert soluble nutrients into insoluble 

 ones, or to cause the loss of some constituent in the form 

 of gas. If one is to mix his own fertilizers he must know 

 what materials should not be brought in contact. The fol- 

 lowing are some of the common carriers that should not 

 be mixed : 



