The physical analyses of these soils are given below.
PHYSICAL ANALYSES OF TYPICAL SOILS.
| Clay. | Silt. | Sand, 2.0 to 64 mm. h. v. | ||||
|---|---|---|---|---|---|---|
| Fine, < .25 to .5 mm. h. v. | Coarse, .5 to 2. mm. h. v. | |||||
| No. | 233. | Morano sandy soil | 2.82 | 3.03 | 3.49 | 89.25 |
| No. | 1197. | Gila bottom soil | 3.21 | 5.53 | 15.42 | 72.05 |
| No. | 198. | Ventura silty soil | 15.02 | 15.24 | 25.84 | 45.41 |
| No. | 1697. | Berkeley adobe soil | 44.27 | 25.35 | 13.47 | 13.37 |
The most striking feature in this diagram is the very rapid[74] and high ascent in the combination of sediments represented by the Gila bottom soil. It outstrips at once both the sandy soil from Stanislaus, which contains a trifle less of clay, and the silt soil from Ventura, from which at first sight it does not seem to differ widely, but which contains considerably more clay. It is doubtless the latter which so greatly retards the motion of the water, as is still farther seen in the case of the clay or adobe soil. It will be noted that on the second and third days, the Gila soil had raised the water nearly twice as high as the adobe, and that it took only 18 hours to raise it nearly the same height as that attained by the Ventura silt in so many days. But it ceased to rise after the 125th day, while the Ventura soil, continuing for 195 days, finally rose 3 inches higher. The adobe also continued its rise, but did not reach the same height as the Gila soil by nearly two inches. There can be no doubt that the energetic and high rise of the latter proves an important factor in the culture of these lands.
The coarse sandy soil reached its highest limit, 16½ inches, within six days, when the silty Gila soil stood at about double that height.
Fig. 38.—Columns showing heights to which
water will rise by capillarity in soils of
different physical composition,
and rates of ascent.
Fig. 39.—Capillary Rise of Water in Soil
Sediments of different Diameters.
Ascent of Water in uniform[75] Sediments.—Loughridge has ascertained the rate of ascent of uniform sediments of different grain-diameters, with the results shown in the diagram subjoined, together with the maximum height reached by each. The diagram is very eloquently illustrative of the great differences in the capillary properties of granular sediments of the various grades; and it would seem that it ought to be possible to deduce from it by a somewhat complex formula the rate and height of ascent of water in any soil of known physical composition. In nature, however, the presence of clay and the greater or less degree of flocculation of mixed sediments will always vitiate to a very great extent the results deducible from such calculations; hence the data conveyed by the observations of Loughridge must be considered applicable only to granular sediments free from clay and entirely deflocculated.