. The nature and properties of soils; a college text of edaphology. Soils. 74 NATUEE xND PEOPEETIES OF SOILS conversant with these various values, a mechanical analysis should reveal at a glance certain soil conditions, which may- or may not be conductive to the best plant growth. The sands and the gravel, because of their sizes, function as separate particles. They are irregular and rounded, the continual rubbing that they have received being sufficient in many cases to have ef- faced their angular char- acter. They exhibit very low plasticity and cohe- sion, and as a consequence are little

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. The nature and properties of soils; a college text of edaphology. Soils. 74 NATUEE xND PEOPEETIES OF SOILS conversant with these various values, a mechanical analysis should reveal at a glance certain soil conditions, which may- or may not be conductive to the best plant growth. The sands and the gravel, because of their sizes, function as separate particles. They are irregular and rounded, the continual rubbing that they have received being sufficient in many cases to have ef- faced their angular char- acter. They exhibit very low plasticity and cohe- sion, and as a consequence are little
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Image ID: PFXPAW
. The nature and properties of soils; a college text of edaphology. Soils. 74 NATUEE x\ND PEOPEETIES OF SOILS conversant with these various values, a mechanical analysis should reveal at a glance certain soil conditions, which may- or may not be conductive to the best plant growth. The sands and the gravel, because of their sizes, function as separate particles. They are irregular and rounded, the continual rubbing that they have received being sufficient in many cases to have ef- faced their angular char- acter. They exhibit very low plasticity and cohe- sion, and as a consequence are little influenced by changes in water content. Their water-holding ca- pacity is low, and because of the large size of the spaces between each sep- arate particle the passage of percolating water is rapid. They, therefore, facilitate drainage and encourage good air move- ment. In all the grades of sand, the separate par- ticles are visible to the naked eye, a condition impossible with the silt and clay groups. Soil containing much sand or gravel, there- fore, is of open character, possessing good drainage and aeration, and is usually in a loose friable condition. The clay and silt particles are very minute, many of^ the former being so small as to be invisible under the ultra-micro- scope. Both groups are really shreds and fragments of min- erals often rather gelatinous in nature. The clay particles are highly plastic and when kneaded with just the correct. a Pig. 15. — Apparatus for making^ mechanical analysis of soils. Shaker-bottle (A), shaking-rack (B), sieves (0), centrifuge (D) and cen- trifuge-tube (S).. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original work.. Lyon, T. L. (Thomas Lyttleton), 1869-1938; Buckman, Harry Oliver, 1883-. New York, Macmillan

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