CAPILLARY MOVEMENT OF SOIL MOISTURE. 



17 



The distance moved in 2 hours, in percentage of the total distance 

 moved in 30 days, or 720 hours, was as follows : 



Flume 19, 20 per cent; flume 43, 13 per cent; flume 63, 13 per cent; 

 flume 80, 13 per cent; flume 100, 9 per cent; flume 209, 36 per cent. 

 In 2 hours, or 1/360 of the time, the percentage ranges from 36 in the 

 light Idaho soil to 9 in the heavy Idaho soil, or from about one-tenth 

 to about one-third the total distance. 



About the same relative rate of movement of moisture for the first 

 few hours of the exjDeriment is shown by Table 2. In the first 8 

 hours, or one-third of the 24 hours, the moisture had moved upward 

 more than 70 per cent of the total distance moved in 24 hours, while 

 in the longer period of 30 clays it is found that more than 80 per cent 

 of the total distance was covered in one-third of the time. 



The above tables and diagram but emphasize and give in some de- 

 tail the rapid action of capillary moisture when soils are first placed 

 in contact with free water, and show that a large part of the total dis- 

 tance the moisture will move in a month is covered within the first 

 few hours. These results are in accord with those obtained by 

 others. (9) 



WATER USED. 



The figures within the small circles in figure 2 give, in liters, the 

 total quantity of water removed from the tanks by the soil columns 

 at the end of various periods of time. 



At the end of 30 days, flume 63 had taken about 30 per cent more 

 water than had flume 19, and flume 100 had taken up nearly twice as 

 much water as flume 19. Flume 209 used very little water after the 

 first 6 days and a large part of the total water used in the 30 clays 

 was used the first clay. At the end of 30 days this flume had used only 

 about one-half as much water as flume 19. These figures show, as 

 was to be expected, that the lighter soils require less water per inch 

 than do the heavier soils. 



Table 3. — Quantity of water used to move moisture an average distance of 1 

 ■inch at the end of different periods of time. 









Flume . 







Number 

 of days. 



























19 



43 



C3 



80 



100 



2C9 





Liters. 



Liters. 



Liters. 



Liters. 



Liters. 



Liters. 



1 



0.422 



0.446 



0.700 



0.250 



0.482 



0.296 



2 



.393 



.526 



.737 



.256 



.468 



.276 



3 



.392 



.506 



.726 



.323 



.506 



.265 



4 



.379 



.500 



.772 



.311 



.527 



.259 



10 



.366 



.470 



.789 



.326 



.497 



.254 



20 

 30 



.364 

 .357 



.484 

 .472 



.840 

 .816 



.317 

 .327 



.488 

 .484 





.239 



147697°— 20— Bull. 835- 



