336 



PRINCIPLES OF AGRICULTURAL CHEMISTRY 



On this particular soil, with the amounts of fertilizers used and 

 crops grown and at the prices given, phosphoric acid alone was 

 profitable, potash and nitrogen being applied at a loss in both 

 cases. On other soils and with other crops, different results 

 would be secured. These figures are merely given to show the 

 method of calculating. Additional expense due to handling the 

 increased crop, and the fertilizer, should also be considered. 



Systems of Fertilization. There is a great diversity in soils, 

 crops, climatic conditions, and other factors which modify the 

 effect of fertilizers. Individuals must study their own condi- 

 tions, try various combinations, and use such mixtures as give 

 most profitable results under their conditions. Fertilizers which 

 give good results are recommended in the various publications on 

 the subject, but the application which will be the best and the 

 most profitable will depend upon individual conditions. 



Systematic use of fertilizers is more profitable than haphazard. 

 The following are some of the systems 1 which are used. Every 

 system should include a rotation of crops, with liberal use of 

 manure or green crops plowed under. 



i. System Based on Influence of a Single Element. This 

 system assumes that plants can be divided into three groups ; one 

 group most benefited by nitrogenous fertilizers, another by phos- 

 phatic, and the third by potassic. Nitrogen is said to be the 

 dominant element for wheat, rye, oats, barley, meadow grass, and 

 beet crops. Phosphoric acid is dominant for Indian corn, sorg- 

 1 Voorhees' Fertilizers. 



