Mar. i, 1924 
Movement of Water in Irrigated Soils 
619 
per cent of that cubic foot weighs 30.26 pounds. If the dry soil in this 
cubic foot weighs 85 pounds, then 100 pounds of soil under the same con¬ 
dition of saturation would hold 35.6 pounds of water. 
In like manner it is possible to compute the pore space and the water¬ 
holding capacity in percentage of water to the dry weight of the soil for 
any given case where the volume mass of the dry soil is known. Table I 
shows these relationships for several different weights of soil, and these 
are presented graphically in figure 1. 
Fig. 1 .—Diagram showing water-holding capacity of soil at densities ranging from 70 to 125 pounds 
per cubic foot, based on specific gravity of 2.65. 
Table I .—Pore space in dry soil of different weights per cubic foot based on the specific 
gravity of 2.65 for the soil material and the moisture content if this pore space were filled 
with water 
| Weight of 
{ dry soil per 
1 cubic foot. 
Pore space. 
Water in 
saturated 
soil. 
Water per 
foot of soil.« 
Pounds. 
Per cent. 
Per cent. 
Inches. 
70 
57-6 
51-4 
6.9 
75 
54 * 6 
45*4 
6- 5 
80 
5 i -5 
40. 2 
6. 2 
35 
48.5 
35-6 
5-8 
90 
45 - 5 
3 i- 5 
5 - 5 
95 
42.4 
27.9 
5 - 1 
100 
39-4 
24. 6 
4-7 
105 
36. 4 
21. 6 
4.4 
no 
33-3 
18. 9 
4. 0 
ii 5 
30*3 
16. 4 
3-6 
120 
27*3 
14. 2 
3-3 
125 
24. 2 
12. 1 
2.9 
a By this is meant the equivalent, in inches in depth, of water contained in each foot in depth of soil. 
It is not always an easy matter to determine the volume mass or the 
weight per cubic foot of the dry soil as it occurs in field conditions. The 
soil in the field is never entirely dry, and it may lose volume as well as 
weight when dried after being taken from its position in the field. It is 
this property of the soil by which it tends to increase its volume when 
