40 



THE PHYSICAL PROPERTIES OF SOILS 



with the soil in the cyhnders and allow to 

 stand until free moisture appears on the 

 surface. Remove from the tank, wipe 

 dry, and weigh immediately. Then place 

 the cylinders on a draining board, under 

 a bell jar (T) and weigh every forty- 

 eight hours for a week. 



Tabulate the weighings and calculate 

 the per cent of water required to saturate 

 each soil and the per cent of capillary 

 w^ater retained in each after seven days 

 of drainage. Discuss the factors effect- 

 ing the water-holding power of soils. 



Reference: 



Burkett, ''Soils," pp. 40-42. 



II. THE DISTRIBUTION OF CAP- 

 ILLARY WATER IN SOIL COL- 

 UMNS. 



Prepare two 36-inch brass cylinders 

 (T) in the manner described above, 

 using sand in one and loam or silt in the 

 other. At the end of the drainage period 

 make moisture determinations at inter- 

 vals throughout the length of the columns 

 by means of samples taken through the 

 side tubes provided for that purpose. 



How is the moisture distributed? 

 Explain the cause of the unequal dis- 

 tribution. 



References : 



Hall, "The Soil," p. 64. 



m 



I 

 I 



M 



S 



i 



CM 



.-iK 



BRASS CYLINDER 



Provided with side tubes 

 for studying the distri- 

 bution of moisture in 

 vertical columns of soil. 



King, 'Thysics of Agriculture," |:j%t^' raUM-ai" mov^: 



mcnt of capillary mois- 

 ture. 



p. 114. 



