CAPILLARY MOVEMENT OF SOIL MOISTURE. 



63 



CAPILLARY MOVEMENT OF MOISTURE FROM A WET TO A DRY 



SOIL. 



- As has been stated previously, the movement of moisture by capil- 

 larity is much slower and not so extensive in the absence of free 

 water as it is in the presence of free water. When a wet soil and a 

 dry soil are in contact, gravity exerts an appreciable influence in the 

 capillary movement of moisture. 



The experimental work so far done at Riverside does not war- 

 rant more than a few general statements. To give some idea of the 

 nature of this work a few experimental results will be given. 



THE VERTICAL BOXES. 



The soil boxes were placed in vertical and horizontal positions only. 

 In the vertical boxes the wet soil was placed in some cases on top, 

 in others at the bottom, and in others the wet soil was placed in the 

 middle section and dry soils at both ends. 



Nearly all boxes were 6 feet in length and the wet soil occupied 

 one half this length and the dry soil the other half. 



MOVEMENT OF MOISTURE TJPWAED. 



In table 43 are given data of a few of the boxes in which the soil 

 moistened to the percentages shown were placed at the lower ends of 



Table 43. — Movement of moisture upward in tJw boxes. 



Days. 



Riverside soil, 

 initial percentage. 



Idaho lava soil, 

 initial percentage. 



Whittier soil, 

 initial psrcentage. 



20 per 

 cent. 



10 per 

 cent. 



14 per 

 cent. 



20 per 

 cent. 



25 per 

 cent. 



40 per 

 cent. 



30 por 



cent. 



1 



4 



5 



G 

 7 

 8 

 9 

 11 

 12 

 14 

 18 

 23 

 26 

 37 

 40 

 49 

 56 

 71 

 E6 



Inches. 

 1.12 

 2.25 

 3.00 

 3.37 

 4.0O 

 4.50 

 4 82 

 5, 00 

 5.37 



Inches. 



Inches. 



Inches. 

 1.50 



Inches. 



Inches. 



Inches. 





1.00 







1.25 



1.25 









2.25 



















2.00 



1.83 































3.25 



4.50 





2.25 



2.75 





7.00 







6.50 









4.50 







8.37 



4.37 



3.25 



7. 75 









1.70 



1.00 

 1.75 



10. 75 





3.50 



6-, 83 







10.50 

 11.00 

















12.75 











6.50 

















14. 25 









1 









the boxes and air-dried soils at the upper ends. The table shows 

 that the box containing the Eiverside' soil, with the lower half 20 per 

 cent of moisture, the movement of the moisture up into the dry soil 

 was about one-fourth as great in 4 days as it was in 56 days. In the 

 box of Eiverside soil, containing 10 per cent moisture in the wet 



