Agricultural Chemistry. 



for the maximum growth of the plant should be. And even if 

 we had such information, the makers of fertilizer mixtures en- 

 tirely disregard the quantities of plant food already existing in 

 the soil to be treated. When the farmer studies the apparent 

 needs of his fields and understands the subject of fertilization of 

 ^rops, he will prefer to buy the basal fertilizing materials of defi- 

 nite, known composition and make the proportion best adapted 

 to his needs, rather than buy mixed fertilizers. 



High and low grade fertilizers. As the basal materials used 

 in compounding fertilizing mixtures differ greatly in the amounts 

 of plant food they contain, it will be seen that products made by 

 mixing these materials will contain very different percentages of 

 nitrogen, phosphoric acid and potash. If, for example, dried 

 blood, bone meal and muriate of potash were used, the fertilizer 

 would have a high content of plant food, while if low grade tank- 

 age, wood ashes, or kainit were employed, the product would 

 have a low percentage. The first example illustrates a high 

 grade product, while the second would be considered as low 

 grade. 



As the low grade material can be sold at a comparatively low 

 price, these materials find a ready market, although the plant 

 food in the cheap fertilizer actually costs more per pound. This 

 fact is clearly brought out in the following table taken from a 

 recent bulletin of the New York Experiment Station. (Geneva). 

 Average Cost of One Pound of Plant Food to Consumers. 



