The Storage and Use of Soil Moisture 
33 
dry soil the movement is so retarded and the amount of water 
required to moisten it so great, that the water from a single rain, 
coming alone, is generally held near the surface. From here it is 
soon lost thru the rapid evaporation which takes place at the 
surface. On the other hand, where the soil is already moist when 
the rain comes, it is much more quickly carried away from the 
surface, thus giving place for more water from the rain to be 
held at the surface. It is also distributed to lower depths in the 
soil and thus protected from the rapid loss at the surface. Fre- 
quent observations have been made along this line on the native 
sod. This is usually hard and dry. It is seldom wet more than a 
few inches by the rains that come singly. The lower depths re- 
ceive moisture only during "rainy" or "wet spells" when a second 
rain comes before the moisture from the preceding rain is lost. 
In the following tables are given data bearing upon these 
points : 
Table C. — Effect of surface condition in retaining rainfall, 1908. 
PER CENT MOISTURE IN THE SOIL. 
Depth 
Sod land 
Corn land 
May 11 
May 15 
Gain 
May 12 
May 15 
Gain 
Feet 
1 
16.8 
21.0 
4.2 
18.5 
20.6 
2.1 
2 
8.7 
8.6 
11.0 
16.4 
5.4 
3 
7.3 
7.6 
9.4 
9.6 
Table 6 gives data to show the effect of the surface condition 
on the amount of water held. During the interval between the 
sampling dates 1.62 inches of water fell. This fell as three rains, 
the greatest of which was .86 inch and fell very rapidly. The 
samples were taken twenty-four hours after the last rain. 
Table 7. — Effect of surface condition and moisture content on 
storing water, 1909. 
PER CENT MOISTURE IN THE SOIL. 
Depth 
Brome grass sod 
Cora land 
Sept. 3 
Sept, 4 
Gain 
Sept. 3 
Sept. 4 
Gain 
Inches 
. 1-3 
9.5 
15.3 
5.8 
12.4 
17.1 
4.7 
4-6 
6.4 
6.5 
13.3 
16.2 
2.9 
7-9 
6.9 
6.6 
13.6 
15.2 
1.6 
10-12 
6.8 
6.5 
13.3 
13.2 
