Field Analysis:How Texture
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[edit] How to Record Soil Texture?
The recording scheme used here is based on the U.S. Dept. Agriculture system which recognises loam and silt as separate categories.
A scheme for determining texture class from a ball of moist soil worked between the fingers is given below.
[edit] Sand grain size
Further distinctions can be made between fine, medium and coarse sand.
- Fine sand - Is barely visible, but still feels slightly gritty when rubbed between the fingers. This grades into the silky feeling of silt for very fine sand.
- Medium sand – Individual grains are visible, and soil has a distinct gritty feeling when rubbed between the fingers.
- Coarse sand – Individual grains clearly visible, and feels very gritty when rubbed between fingers.
[edit] Sorting
Sorting refers to the distribution of different particle size classes in a soil or sediment. A very well sorted deposit will contain only particles of very similar size. A very poorly sorted deposit will contain a particles with a very wide range of sizes from clay to large stones.
Some soils or sediments may contain two distinct sizes of particles, for example clay and coarse sand. This is called a bimodal particle distribution and should be recorded in general comments.
Sorting includes the stone content
