THE FORMS OF SOIL WATBB 



lU mJl 



Soil 



Per- 

 cent- 

 age OP 

 Or- 

 ganic 

 Matter 



Per- 

 cent- 

 age 



OP 



Sands 



Per- 

 centage 

 OF Silt 



Per- 

 centage 



OF 



Clay 



Mois- 

 ture 



Equiva- 

 lent 



1. Norfolk coarse sand . 



2. Norfolk fine sandy loam 



3. Yazoo loam .... 



4. Waverly silt laom . . 



5. Houston clay loam . 



6. Houston clay . . . 



.9 

 1.3 

 1.3 

 2.0 

 3.7 

 1.4 



87.9 

 73.4 



^5.8 

 14.9 

 30.9 

 10.0 



7.3 

 18.1 

 64.1 

 62.9 

 42.5 

 56.6 



4.8 

 8.5 

 10.1 

 22.2 

 26.6 

 33.4 



4.6 



6.8 



18.9 



24.4 

 32.4 

 38.2 



149. The maximum retentive power of a soil. — An- 

 other determination has been devised by Hilgard ^ and 

 used to considerable extent by other investigators.^ It 

 is designated as the maximum retentive power of a soil. 

 A small perforated brass cup is used, having a diameter 

 of about 5 centimeters and capable of containing a soil 

 column 1 centimeter in height. A short column is used, 

 since it is only under such conditions that a soil may re- 

 tain against gravity the greatest amount, of water. Also, 

 the soil is able to expand or contract, as the case may be, 

 on the assumption of water until an equilibrium is reached. 

 A filter-paper disk is placed in the metal cup, and the soil 

 is poured in, gently jarred down, and stroked off level 

 with the top of the cup. The cup is then set in water 

 and the soil is allowed to take up its ma^iuxn moisture. 

 After draining, the weight of the wet soil plus the cup, 

 together with the weights previously obtained, will allow 

 the calculation of the total water contained by the soil 



150. Capillary movement. — It has already been shown 

 how different thicknesses of films on two particles tend 



1 Hilgard, E. H. Soils, p. 209. New York. 



2 This text, paragraph 181. 



1911. 



