98 NATURE AND PROPERTIES OF SOILS 



crop growing on the soil, when such a large amount of sur- 

 face is continually available for chemical action. 



53, Resume. — The discussion of the soil particle as to its 

 size, its classification, its chemical characteristics, and its 

 mineralogical peculiarities is undoubtedly important. Im- 

 portant also are the specific physical properties which arise 

 because of textural and structural make-up, such as specific 

 gravity, volume weight, pore space, and immense internal 

 surface. These phases, however interesting in themselves, 

 must not be studied so closely as to prevent their broad and 

 vital plant correlations from becoming evident. None of the 

 transformations concomitant with normal crop production 

 takes place in the soil without definite and widespread co- 

 operation. The study of the soil particle is, therefore, more 

 than a consideration of a few interesting physical and chem- 

 ical phenomena. From such investigations have been devel- 

 oped and perfected the broad principles which govern suc- 

 cessful soil management and economical food production. 



