CAPILLARY MOVEMENT OF SOIL MOISTURE. 



21 



100, maintain a rather uniform percentage of moisture throughout 

 the 30 days. (The distribution of this moisture throughout the col- 

 umn will be given later.) At the end of 62 days flume 63 contained 

 in the wet soil by volume 47 per cent of water, or a little less than at 

 the end of 30 days. At the end of 44 days flume 100 contained by 

 volume 29.8 per cent of water, or about the same percentage contained 

 for the first 30 days. 

 Table 8. — Percentage, by volume, of water in wetted soil at end of time specified. 



Number 

 of days. 



Flume. 



19 



43 



03 



80 



100 



209 



1 

 2 

 3 



4 

 10 

 20 

 30 



Per cent. 

 25.7 

 24.0 

 23.9 

 23.1 

 22.3 

 22.0 

 21.8 



Per cent. 

 27.2 

 32.2 

 31.0 

 30.5 

 28.0 

 29.4 

 28.8 



Per cent. 

 42.6 

 45.0 

 44.3 



Per cent. 

 15.3 

 15.6 

 19.9 

 19.3 

 19.9 

 19.4 

 20.6 



Per cent. 

 30.0 

 28.6 

 30.6 

 32.0 

 30.3 

 29.0 

 . 29.6 



Per cent. 

 18.0 

 16.9 

 16.1 

 15.8 



48.2 

 51.7 

 50.0 





14.5 



Table 9. — Distribution of mois- 

 ture in vertical soil columns. 



Table 8 would indicate further that capillary action must take 

 place much slower in heavy soils than in light soils, due to the rela- 

 tively higher percentage of moisture in the heavy soils at all points 

 in the column. It takes a higher relative percentage of moisture 

 in the heavy soils to permit the advance of moisture from a damp 

 to a dry soil by capillary action. The lighter soils will contain a rela- 

 tively smaller percentage of moisture in the very extremity of the 

 wetted area as it advances than will the heavier soils. 



DISTRIBUTION OF SOIL MOISTURE IN VERTICAL SOIL COLUMNS. 



The distribution of moisture in a vertical column of soil, the lower 

 end of which is in contact with a body of water (9) , has received con- 

 siderable attention in these experi- 

 ments. The study has included the dis- 

 tribution for the various lengths of 

 time up to and including 40 days. In 

 Table 9 is given the distribution in two 

 vertical columns for periods of 30 days, 

 or after the column has been in contact 

 with the water for a period of 30 days. 

 Flume 43 is Riverside soil No. 1, and 

 flume 63 is the Whittier soil. Flume 

 63 was closed to evaporation, while 

 flume 43 was open upon one side, and 

 the soil is held in place by brass- wire 

 gauze. 



The figures show that the decrease 

 in the percentage of moisture from 



the water surface to the upper extremity of the wetted area is 

 not uniform. In flume 43, the greatest percentage of moisture is 



Distance 







above 



Riverside 



Whittier 



water 



soil No. 1: 



soil: 



level 



Flume 43. 



Flume 63. 



(inches). 









Per cent. 



Per cent. 



1 



17. 40 ■ 



43.74 



3 



17.40 



45.53 



C 



20.44 



40.25 



9 



18.84 



40.70 



12 



12.67 



40.84 



15 



18 





33.11 

 33.49 



12. G5 



21 



24 





34.75 

 30.82 



12.44 



2S 

 30 

 31 

 36 





24.59 



10.15 



5.59 

 4. CO 



6.33 



