SOME PHYSICAL PROPERTIES OF THE SOIL 125 



sands 1 agreed rather closely (see Fig. 20). The effective 

 diameter of the particles of some of our common soils, to- 

 gether with the effective surface exposed, is given 

 below : 2 — 



Soil 



Coarse sandy soil 

 Sandy soil . 

 Sandy loam . 

 Loam . . . 

 Loamy clay soil 

 Fine clay son* . 

 Very fine clay 



Effective 

 Diameter 



.1432 mm. 

 .0755 mm. 

 .0303 mm. 

 .0219 mm. 

 .0140 mm. 

 .008(1 mm. 

 .0049 mm. 



Percentage 



of Pore 



Space 



34.9 

 34.4 

 38.8 

 44.1 

 45.3 

 48.0 

 52.9 



Effective Sur- 

 face Exposed in 

 One Cubic Foot 

 of Soil 



8,318 sq. ft. 



15,870 sq. ft. 



36,880 sq. ft. 



46,510 sq. ft. 



71,316 sq.ft. 

 110,500 sq. ft. 

 173,700 sq. ft. 



The method of King has certain advantages, besides 

 giving an idea as to the number of particles, their internal 

 •surface, and the relation of this internal surface to soil 

 conditions. In the first place, a single figure is used 

 to express the size of particle ; secondly, from this effec- 

 tive size of particle the probable rate of air and water 

 movement may be calculated ; and, thirdly, the number 

 of particles and the internal surface calculated therefrom 

 have a fairly definite relationship to the plant, as such 

 figures are so closely correlated to the circulation of air 

 and water. 



1 King, F. H. Physics of Agriculture, p. 123. 

 by the author, Madison, Wisconsin. 1910. 



mid., d. 124. 



Published 



