CAMPBELL'S SOIL CULTURE MANUAL 103 



"I believe that through the results of our investiga- 

 tions during the last twelve years we are beginning to 

 understand clearly the chemistry of the soil. It is exceed- 

 ingly interesting, but it is entirely different from our 

 former conceptions of it. We are changing our ideas 

 about the chemistry of the soil as we are changing our 

 ideas about the nature of diseases and about physical 

 forces and physical laws which we thought were perfectly 

 understood." 



It need not be regarded as at all surprising therefore, 

 that practical farmers and experimenters should be chang- 

 ing their views as to the chemistry and the physics of the 

 soil, and in regard to soil management, since those who 

 have had such opportunities for knowing the truth admit 

 now that their views are changing because of modern 

 investigations. 



And this is true that investigation is giving us new 

 light on the soil and on the nature of soil fertility, and 

 we are finding out a great many new things about the 

 relationship which a certain physical condition of the soi 

 through cultivation bears to the fertility of the soil and 

 to plant growth. 



The soil is not alone the home of the plant and a place 

 for its roots to take hold and keep the plant erect; the soil 

 is the source of food supply for the plant, and the supply 

 is there in proportion to the intelligence of the tiller of 

 the soil in his preparation for it. 



Instinctively, almost, the possessor of land that is 

 poor in crop producing qualities turns to fertilizers as his 

 hope. But he often discovers that he^ has not been able 

 to secure soil fertility by the application of fertilizers. 

 He is puzzled, but he does not find any solution to the 

 puzzle. The Department of Agriculture reports experi- 



