

^ CHAPTER III. 



THE SOIL 



By Roy Hansen, M.S., Professor of Soils, University of 

 Saskatchewan, Saskatoon. 



27. The Role of the Soil. — The existence of mankind is 

 dependent upon three things : the earth, the atmosphere 

 and the sunshine. Of these, only the earth is subject to 

 the will of man, to conserve or destroy according to his 

 knowledge or ignorance. And of the earth, it is with the 

 shallow surface crust, but a few inches in thickness, 

 which we designate as "the soil", that we are most con- 

 cerned. The soil must support the plant world which in 

 turn supports the animal world, including mankind. 

 Thus the food we eat, the clothes we wear, and the 

 timber that provides us shelter come ultimately from the 

 soil. The soil, therefore, is our greatest resource, the 

 very foundation of life and prosperity. 



The growing plant in its endeavor to reproduce its 

 kind, the chief function of all life, had need of five 

 essentials : ( 1 ) a place to take root, that it may support 

 its aerial parts; (2) food, as important to plants as it 

 is to animals; (3) moisture; (4) heat; (5) light. 



With the exception of light the soil is concerned in 

 each of these essentials. The root system of the plant is 



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