BxJBEAu OP Agbiotjltubb. 158 



of soil fertility and pointed out how, in many instanoes, 

 through improper systems of cropping, failure to use 

 legumes and cover crops, and how by failure to return 

 to the soil the manurial equivalent of the crops removed, 

 and how through leaching and the burning out of humus, 

 the soils of the State were becoming unproductive. It 

 was further pointed out in this bulletin that while com- 

 mercial fertilizers have their place in agriculture, we 

 cannot make them our sole or chief dependence in main- 

 taining soil fertility. If a soil is deficient in phosphoric 

 acid or potash, or both, then phosphates or potash, or 

 both, should be bought as needed. As a rule, nitrogen 

 should not be bought, but should be returned to the soil 

 in farm manure and produced by the growing of legum- 

 inous crops. The practice of buying complete fertilizers, 

 without any consideration of the deficiencies of the soil, 

 is very wasteful. 



"Small applications of commercial fertilizers may, 

 and do sometimes, prove profitable, but it is because 

 they supply a small amount of readily available plant 

 food at the beginning of the growing period, thus stim- 

 ulating the plant and making it more vigorous, and, 

 therefore, more able to draw upon the soil for its food. 

 But the farmer should not deceive himself in believing 

 that the fertilizer used has fed his crop. It has caused 

 the plant to draw more heavily upon the soil and exhaust 

 it more rapidly. This is the real reason for the belief 

 that commercial fertilizers injure the soil. The small 

 applications of fertilizers commonly used will, as a rule, 

 give more profitable results on good soils than on poor 

 ones. Although commercial fertilizers may be used, the 

 farmer should not for an instant neglect the care of farm 

 manure, the growing of leguminous crops, and the prac- 

 tice of adequate crop rotation. ' ' 



"Then the functions of commercial fertilizers are, 

 first, to supply a deficiency or deficiencies, and, second, 

 to strengthen the plant at the beginning of the growing 

 period. It is, therefore, important for the farmer to de- 

 termine by field tests just what the fertilizer require- 

 ments of his soil are. ' ' 



This bulletin also outlined a plan for determining the 

 fertilizer requirements of a given soil by a system of ex- 



