THE PRINCIPLES OF FERTILIZER PRACTICE 479 



A brand of fertilizer is usually made up of a number of 

 materials containing the important nutrient ingredien ts. 

 These materials, already described, are called carriers . The 

 making-up of a commercial fertilizer consists in mixing the 

 various carriers together so that the required percentages of 

 ammonia, potash, and phosphoric acid are obtained, care being 

 taken that no detrimental reaction shall occur and that a 

 physical condition consistent with easy distribution shall be 

 maintained. Brands of fertilizer put out by reputable com- 

 panies carry a large proportion of their nutrients in a readily 

 available form. A fertilizer made up principally of dried 

 blood, tankage, acid phosphate, and kainit or muriate of pot- 

 ash is a good example of the ordinary composition of ready 

 mixed goods. 



The various brands on the market, besides being complete 

 or incomplete, may be designated as high-grade or low-grade 

 as to availability, or high-grade or low-grade as to amount of 

 plant nutrients carried. In the fertilizer trade the terms 

 generally refer to the latter condition. A low-grade fertilizer 

 in the latter sense is always encumbered with a large amount 

 of inert material, called filler, which adds to the cost of mix- 

 ing, transportation and handling. A low-grade fertilizer is 

 generally more expensive a unit of* nutrient obtained than 

 are higher grade goods, and consequently should be avoided. 



Fertilizer concerns have always found it more profitable to 

 sell ready mixed fertilizers than to deal in the separate car- 

 riers, such as dried blood, muriate of potash, and the like. Of 

 late years, however, it has been possible to buy the separate 

 materials. The conditions during the World War greatly 

 encouraged the application directly to the soil of separate 

 carriers, especially acid phosphate, since potash was almost 

 unobtainable and nitrogen fertilizers were very high in price. 

 The use of phosphoric acid alone is often much more eco- 

 nomical and rational than the use of a complete mixture, since 

 the nitrogen removed from the soil by normal cropping and 



