568 SOILS: PBOPERTIES AND MAJSfAGWMENT 



with germination and may also injure the young plants. 

 Also, it is likely to result not only in a poor physical condi- 

 tion but also in uneven distribution, which will bring about 

 a lo^\ered efficiency of the fertilizer. The use of sufficient 

 dry, finely divided filler will obviate such dangers. 



477. Factors affecting the efficiency of fertilizers. — 

 The agricultural value of a fertilizer is necessarily a vari- 

 able quantity, since, in applying fertilizers, a material 

 subject to change is placed in contact with two wide 

 variables, the soil and the crop. The general factors 

 that govern the effect of fertilizers may be listed as 

 follows : — 



1. Seed, crop, and adaptation of crop to soil. — It is quite 



evident that different crops will respond differ- 

 ently to the same fertilizer elements. Also, the 

 strength of the seed, the management of the crop, 

 and the adaptation of crop to soil, will be potent 

 factors in variation. 



2. Tertiperature, sunshine, and rainfall, — These factors 



are meteorological and, of course, are dominant 

 in the growth of the plant. Rainfall especially 

 is important, as an optimum moisture content 

 is conducive * to good plant development. In 

 general, as shown by experiments in Ohio and 

 Pennsylvania, the higher the rainfall, the greategr 

 is the efficiency of the fertilizer used. 



3. Drairmge.- This is of great importance in ferti- 



lizer practice, since it places the soil in a better 

 condition from all standpoints for plant growth. 

 In other words, the better the normal soil condi- 

 tions, the better should be the reaction from ferti- 

 lizer application. 



