Soil texture is a soil property used to describe the relative proportion of different grain sizes of mineral particles in a soil. Particles are grouped according to their size into what are called soil separates (clay, silt, and sand). The soil texture class (eg. sand, clay loam, etc) corresponds to a particular range of separate fractions, and is diagramatically represented by the soil texture triangle. Coarse textured soils contain a large proportion of sand, medium textures are dominated by silt, and fine textures by clay.

Soil separate

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A soil separate is a specific range of particle sizes. The larger sizes are described as coarse, intermediate as medium, and the smaller as fine. (Different methods of soil texture classification define the separates slightly differently.)

Name of soil separate	Diameter limits (mm) (USDA classification)
Clay	less than 0.002
Silt	0.002 - 0.05
Very fine sand	0.05 - 0.10
Fine sand	0.10 - 0.25
Medium sand	0.25 - 0.50
Coarse sand	0.50 - 1.00
Very coarse sand	1.00 - 2.00

Major texture classes

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There are 12 major texture classes:

• Sand
• Silt
• Clay
• Loam
• Loamy sand
• Sandy loam
• Sandy clay loam
• Sandy clay
• Silt loam
• Clay loam
• Silty clay loam
• Silty clay

References

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• Soil Texture, by R. B. Brown, University of Florida, Institute of Food and Agricultural Sciences.

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