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Sand particles are relatively large (by definition from 2- to 5-hundredths of a millimeter across). Clay particles are very small (by definition less than 2-thousandths of a millimeter across).
If the percentages of sand, clay, and silt in the soil sample are known, then the triangle can be used to determine the soil texture classification. For example, if a soil is 70 percent sand and 10 percent clay then the soil is classified as a sandy loam. The same method can be used starting on any side of the soil triangle.
[11] [12] Sand is least active, having the least specific surface area, followed by silt; clay is the most active. Sand's greatest benefit to soil is that it resists compaction and increases soil porosity, although this property stands only for pure sand, not for sand mixed with smaller minerals which fill the voids among sand grains. [13]
Silt – Soil type consisting of fine grain deposits that offer good water retention but poor drainage. It is more fertile than sand. Silex – A flint- and sand-based soil type found primarily in the Loire Valley that is a formed from a mixture of clay, limestone and silica. [2] Slate – Soil type that is the most common found in the Mosel ...
Soil types by clay, silt and sand composition as used by the United States Department of Agriculture. Loam (in geology and soil science) is soil composed mostly of sand (particle size > 63 micrometres (0.0025 in)), silt (particle size > 2 micrometres (7.9 × 10 −5 in)), and a smaller amount of clay (particle size < 2 micrometres (7.9 × 10 −5 in)).
Clay particles are finer than silt, being less than 0.002 mm in diameter. Water retention tends to be greater in the finer-textured soils. If a fine-textured soil is well aggregated (with aggregates consisting of numerous organic and inorganic particles bonded together), the large pores between aggregates will facilitate drainage and aeration.
Soil texture triangle showing the USDA classification system based on grain size Map of global soil regions from the USDA. For soil resources, experience has shown that a natural system approach to classification, i.e. grouping soils by their intrinsic property (soil morphology), behaviour, or genesis, results in classes that can be interpreted for many diverse uses.
Vertisols: Usually mollic epipedon; high in shrinking and swelling clays; >30% clay to a depth of 50 cm; deep cracks (called gilgai) form when soil dries; form from parent material high in clay (e.g., shales, basins, exposed Bt horizons of old soils); 2.4% of global and 1.7% of U.S. ice-free land.