198 SOILS AND FERTILIZERS 



lizer, although occasionally a brand of fertilizer will have 

 only two carriers. Each brand is given a trade name, fre- 

 quently implying the usefulness of the fertilizer for some 

 particular crop, but without reference to the character 

 of the soil on which it is to be used. It is better, how- 

 ever, to purchase a fertilizer on the basis of its composi- 

 tion rather than because of its name. The composition 

 of fertilizers for different crops will be discussed later (see 

 § 261). 



If, in compounding a fertilizer, those carriers are used 

 that are difficultly soluble, the fertilizer is not so valuable 

 as if composed of easily soluble substances. The solubility 

 as well as the percentage of each ingredient should be known 

 to the purchaser. 



253. High-grade and low-grade fertilizers. — A fertilizer is 

 known on the market as high-grade or low-grade, depending 

 on the percentage of fertilizing constituents that it contains, 

 or on the availability of its plant-food materials. Low-grade 

 fertilizers cost less than high-grade because thej' contain 

 less plant-food material or because they are less soluble, 

 although the price of a pound of the plant nutrients may be no 

 less, and, in fact, is usually more. The low-grade product 

 is encumbered with a large amount of inert material, that 

 adds to the cost of transportation and handling, without 

 adding to the value of the fertilizer. For these reasons the 

 cost of a pound of any one of the plant nutrients is usually 

 less in high-grade than in low-grade goods. A ton of low- 

 grade fertilizer may contain 500 or 600 pounds more inert 

 material than a high-grade fertilizer, upon which freight 

 must be paid, and which must be hauled from the station 

 and spread on the field. 



The following figures were obtained by tabulating one 

 hundred and thirty brands of fertilizers analyzed at the 

 Vermont Experiment Station. 



