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The WRB lists 40 diagnostic horizons. In addition to these diagnostic horizons, some other soil characteristics may be needed to define a soil type. Some soils do not have a clear development of horizons. A soil horizon is a result of soil-forming processes (pedogenesis). [5] Layers that have not undergone such processes may be simply called ...
The soil suborders within an order are differentiated on the basis of soil properties and horizons which depend on soil moisture and temperature. Forty-seven suborders are recognized in the United States. [6] The soil great group category is a subdivision of a suborder in which the kind and sequence of soil horizons distinguish one soil from ...
An artificially formed aggregate of soil particles can be called a clod. [2] There are five major classes of macrostructure seen in soils: platy, prismatic, columnar, granular, and blocky. There are also structureless conditions. Some soils have simple structure, each unit being an entity without component smaller units.
The color of the ground cover and its insulating properties have a strong influence on soil temperature. [88] Whiter soil tends to have a higher albedo than blacker soil cover, which encourages whiter soils to have lower soil temperatures. [85] The specific heat of soil is the energy required to raise the temperature of soil by 1 °C.
Laterite soils have a high clay content, which means they have higher cation exchange capacity, low permeability, high plasticity and high water-holding capacity than sandy soils. It is because the particles are so small, the water is trapped between them. After the rain, the water moves into the soil slowly.
Water deficiency is the central defining characteristic of Aridisols. Also required is sufficient age to exhibit subsoil weathering and development. Limited leaching in aridisols often results in one or more subsurface soil horizons in which suspended or dissolved minerals have been deposited: silicate clays, sodium, calcium carbonate, gypsum ...
The Unified Soil Classification System (USCS) is a soil classification system used in engineering and geology to describe the texture and grain size of a soil. The classification system can be applied to most unconsolidated materials, and is represented by a two-letter symbol. Each letter is described below (with the exception of Pt):
Thickness of the mollic epipedon ranges from 8 to 20 inches and includes all or part of the Bt horizon. The soil contains 0 to 10 percent by volume of coarse fragments as pebbles. Some pedons contain up to 20 percent by volume of stones throughout. [3] The A horizon has hue of 10YR, value of 3 to 5 and 2 or 3 moist, and chroma of 1 or 2. It ...