630 
Journal of Agricultural Research 
Vol. XXVII, No. 9 
Table VII. Penetration of water in each of five tubes containing soil from the same 
sample 
Time elapsed. 
1 hour. . 
2 hours. 
3 hours. 
4 hours. 
5 hours. 
24 hours 
i 
| Depth of penetration (inches). 
Tube 1 . 
Tube 2. 
Tube 3. 
Tube 4. 
Tube 5 . 
J Mean. 
3- 7 
4.3 
4. 2 
3-9 
4. 5 
4. I 
5* 1 
5- 1 
4. 6 
5-4 
5*o 
5-o 
5-6 
5- 5 
5-o 
5*9 
5-4 
5-4 
6. 0 
5-9 
5-4 
6-3 
5- 8 
5-9 
6.6 
6.5 
5-7 
6.8 
6- 3 
11. 6 
) 
12. 2 
11. 9 
10. 2 
12. 2 
11. 6 
Another example of the differences observed in the rate of water 
penetration in different soils is shown in figure 3. This figure [shows 
diagrammatically the depth of water penetration in glass tubes contain¬ 
ing pulverized dry soil under a fairly constant head of 3 to 4 inches of 
water. The figures in this diagram show that there are very great 
differences in the rate of penetration of water in different soils. It is to 
2* HAS. 
heavy 
HO.J26. 
HEAVY CLAY 
//CAYS. 
HEAVY CLAY CLAY SO/L FROM 
(SALTtfHaJta. HEMCTOH TAACT 
HOWrLEYAAOVECr 
A/O 332. 
F'ig. 3.—Tubes showing rates of moisture penetration in different soils. 
be expected that the texture of the soil has an important bearing on the 
rate of water penetration. This is shown by the more rapid penetration 
in the sandy soil (No. 324) and the loam soil (No. 325) than in the clay 
soils of the other tubes. 
It is not to be inferred, however, that soil texture is the only factor 
or that it is even the most important factor influencing the rate of water 
penetration. It has been shown in Table VI that two sandy loam soils 
which are indistinguishable as to texture show very great differences in 
the rate of water penetration. Similar differences are shown in the base 
of a clay soil from the Belle Fourche reclamation project in South Dakota. 
This Belle Fourche soil is very rich in clay, having been derived from 
the weathering of Pierre shale. The four samples shown in Table VIII 
are all from the same locality and of substantially the same texture. 
One of them (No. 338) was taken from a spot which had been subjected to 
the action of seepage water rich in alkaline salts. The other samples 
were from places that had been watered only by rainfall or irrigated with 
water in which the proportion of alkaline salts was low as compared with 
the salts of calcium and magnesium. 
