398 MISCELLANEOUS FARM SUBJECTS 



and forms of fertilizing materials just described, and the differences 

 that exist in the brands of different manufacturers are due both to 

 differences in the character and to the variations in proportions of 

 the materials used to form the different brands; that is, while all 

 manufacturers must go to the sources of supply they may select 

 either good or poor products and may vary the proportions of the 

 different materials used. The difference between a good brand of 

 fertilizer and a poor one lies not so much in differences that may 

 exist in the total amount of plant food contained in it as in the 

 quality of the materials of which it is made. 



Use of Fertilizer. There is no question as to the desirability 

 I of the use of commercial fertilizers on most farms, though the 

 methods now generally practiced are such as to indicate the very 

 great need of a better understanding of what the functions of a fer- 

 tilizer are, of the terms used to express their composition and value, 

 of the kind that shall be used, and the time and method of applica- 

 tion for the different, crops under the varying conditions that exist. 



The practical point, and the one of prime importance to the 

 farmer, is to know how to estimate the relative value or usefulness 

 of these different products, w T hat is the rate of availability as com- 

 pared with nitrate, and thus the relative advantage of purchasing 

 the one or the other at the ruling market prices. Relative values, 

 however, can not be assigned as yet, though careful studies of the 

 problem have been made, chiefly by what are known as "vegeta- 

 tion tests" that is, tests which show the actual amounts of nitrogen 

 that plants can obtain from nitrogenous products of different kinds, 

 when they are grown under known and controlled conditions. The 

 results so far obtained, while only serving as a guide, indicate that 

 when nitrate is rated at 100 per cent, blood and cotton-seed meal 

 are about 70 per cent, dried and ground fish and hoof meal 65 per 

 cent, bone and tankage 60 per cent, and leather and wool waste 

 range from as low as 2 per cent to as high as 30 per cent. These 

 figures furnish a fair basis for comparing the different materials, 

 when used for the same purpose or under the same conditions. If, 

 for example, the increased yield of oats due to the application of 

 nitrate of soda is 1,000 pounds, the yield from blood and cotton-seed 

 meal would be 700 pounds, the yield from dried ground fish and 

 hoof meal would be 650 pounds, from bone and tankage 600 pounds, 

 and from leather, ground horn, and wool waste from 20 to 300 

 pounds. 



These figures alone are, however, not a sufficient guide as to 

 the kinds to buy under all conditions, since the usefulness of the 

 different forms are again dependent upon such other conditions as 

 the kind of crop, the season, and the object of the application. 



In the making up of fertilizers, all of these considerations should 

 be carefully balanced, and it is the practice on the part of many 

 manufacturers to use a part of each of the three forms, so that a 

 continuous feeding of the plant may be insured. Therefore, while 

 the fact remains mat fertilizers containing only the one form may 



