66 
Journal of Agricultural Research 
Vol. IX, No. 3 
coefficient there was added i inch of water. The cylinders were allowed 
to stand protected from evaporation for five days, and then the moisture 
content of the upper 2 or 3 inches of moistened soil determined. 
Table XXX .—Ratio of moisture content to hygroscopic coefficient in the surface section 
five days after 1 inch of water had been added to the surface of the column of dry soil 
Soil No. 
Hygroscopic 
coefficient. 
Initial 
moisture 
content. 
Moisture 
content. 
Ratio. 
Percent. 
Per cent. 
A. 
13-3 
6.6 
24. 6 
1.9 
B. 
12. 9 
6-3 
22. 2 
i*7 
C. 
10. s 
5*o 
23*3 
2. 2 
D. 
10. 2 
4-9 
26. 4 
2. 6 
E. 
10.1 
5*o 
20 . I 
2. 0 
F. 
10. 0 
4.8 
18.0 
1.8 
G. 
8.2 
3*9 
18 . 0 
2. 2 
H. 
7.6 
3*8 
l 8 . O 
2. 4 
I... 
7* 1 
3 * 5 
18.8 
2. 6 
j .. 
5*6 
2.8 
14. 6 
2. 6 
K. 
3*4 
i*7 
12.3 
3*6 
E. 
3.4 
1. 6 
10. K 
7 . 1 
M... 
O* *r 
3*3 
*•7 
* w ' D 
14 . I 
O’ 
4.3 
N. 
1.7 
.6 
8.8 
5 - 2 
0. 
I. X 
.4 
6.4 
6.6 
P. 
•9 
. 2 
5*9 
6.6 
Q ... 
.6 
. 2 
9.0 
15- 0 
The retardation of movement appears to increase with the decrease in 
the coefficient when this is below 2.0; and even with K, E, and M, with 
coefficients between 3.0 and 4.0, a retardation is apparent during the 
first five days following the application of water, although, as shown 
above, this was not observable after the lapse of two months. 
r6ee of the moisture of the deep subsoie 
From the above statements it would appear that a definite answer may 
be given to the question as to how far the water in the deeper subsoil is 
of importance to annual crop plants. As the minimum to which crops 
can reduce the moisture in the upper subsoil—that traversed by the 
roots—is approximately 1.0 to 1.1 times the hygroscopic coefficient; and, 
as the maximum to be expected in the deeper subsoil is 1.7 to 2.5 in the 
case of loams, it becomes a question of how far and how rapidly the 
moisture in a layer in which the ratio is 2.5 will move upward into an 
overlying layer with a lower ratio of, say, 1.0 to 1.1. The experiments 
have shown that equilibrium may be practically attained when these 
extremes are to be found as close together as 2 feet, or even less, and that 
the movement is so limited that three months was insufficient to restore, 
by upward capillary movement, the small amount of moisture lost 
during 2 % days into the still air of a basement room from the surface of 
soils with a ratio of 1.0. While a very much higher ratio is encountered 
