CHAPTER VII. 



THE BIOLOGY OF SOIL. 



Soil not a dead matrix Organic materials The living 

 organisms of the soil Their activities Their numbers 

 and importance. Abandonment of the notion that 

 chemical analysis can explain the problem. 



It is customary to regard the soil, between the 

 particles of which the root-hairs of plants are dis- 

 tributed, as if it were merely a dead matrix of 

 smaller or larger pieces of rock, such as sand, 

 gravel, stones, etc., and organic remains, such as 

 bits of wood, leaves, bones, etc., with water and 

 air in their interstices. As matter of fact, how- 

 ever, soil is a much more complex body than was 

 suspected until comparatively recent times. 



It is, of course, beyond the scope of this book 

 to go into the different varieties of soils, their 

 structure or arrangement, and the chemical nature 

 of their constituent rocks and the debris mingled 

 with the latter. For the same reason I must pass 

 over the curious properties of soils in relation to 



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