48 SOILS AND FERTILIZERS 



soil, because two soils from the same locality frequently 

 have the same general physical composition and still 

 have entirely different crop-producing powers, due to 

 a difference in chemical composition. 



Attempts have been made to overestimate the value 

 of the physical properties of soils and to explain nearly 

 all soil phenomena on the basis of soil physics. Im- 

 portant as are the physical properties of a soil, it can- 

 not be said that they are or more importance than the 

 chemical properties. In fact the four sciences, chem- 

 istry, physics, geology, and bacteriology, are all closely 

 connected and each contributes its part to our knowl- 

 edge of soils. 



