400 



pends not so much upon what is paid for it as upon the character 

 of the material used to make it. 



The chemical analysis does not show absolutely the sources of 

 the materials, and thus it is difficult to place a true commercial value 

 upon a mixture. This is especially true of organic nitrogen, since 

 because it is impossible to separate the amounts that may be derived 

 from different materials, a uniform value is placed upon the total 

 nitrogen found, whether it is derived from the best forms, as dried 

 blood and dried meat, or whether derived from horn meal, ground 

 leather, or other low-grade forms of nitrogenous materials. This 

 encourages the use of low-grade products by unscrupulous manu- 

 facturers, to the real detriment of the trade as a whole. 



Any system of comparison of brands must leave a great deal 

 to the judgment of the purchaser. He must interpret for himself 

 whether he would rather that his phosphoric acid were derived from 

 one source or another. 



The primary object in the use of a commercial fertilizer is to 

 receive a profit from the increase in the yield of crops from the 

 land to which it is applied; and this may be derived either from 

 the immediate crop or from the larger yield of a number of crops. 

 That the greatest immediate or prospective profit may be gained, a 

 wide knowledge of conditions which have either a direct or indirect 

 bearing upon the result is essential. 



In fact, the controlling conditions surrounding the matter are 

 so numerous and so various that it is impossible, with our present 

 knowledge, to lay down positive rules for our guidance. At best, 

 only suggestions can be offered. 



Modified by Soil. It must be remembered that only general 

 rules apply in the use of fertilizers upon soils of different classes, and 

 that they are modified by both the chemical composition and the 

 mechanical condition of the soil. The best use of a fertilizer that 

 is, the greatest proportionate return of plant food in the crop, all 

 things considered is obtained from its application upon soils that 

 possess condition, or that are well cultivated or managed. Full re- 

 turns cannot be expected when they are applied upon soils that are 

 too w r et or too dry, too porous or too compact, or too coarse or too 

 fine. It is important that even the best soils should be properly pre- 

 pared, and it is infinitely more important that those which possess 

 poor mechanical conditions should be improved in this respect be- 

 fore large expenditures are made for fertilizers. 



The most expensive and irrational system, and one more com- 

 monly practiced than any other in general farming, may be termed 

 the hit or miss system. If a hit is made, there is a profit, if a miss 

 the loss is trifling. In this system no special thought is given to the 

 character of the crop or its needs. If the farmer can afford it, he 

 purchases a fertilizer, without regard to its composition, and applies 

 it in very small amounts. If it happens to contain that element 

 which is particularly needed for the plant to which it is applied, a 

 profit is secured. In too many cases, however, the constituents 



