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Subsoil is the layer of soil under the topsoil on the surface of the ground. Like topsoil, it is composed of a variable mixture of small particles such as sand, silt and clay, but with a much lower percentage of organic matter and humus. The subsoil is labeled the B Horizon in most soil mapping systems. Because it has less organic matter than ...
Soil horizon. A cross section of a soil, revealing horizons. A soil horizon is a layer parallel to the soil surface whose physical, chemical and biological characteristics differ from the layers above and beneath. Horizons are defined in many cases by obvious physical features, mainly colour and texture.
Claypan. Claypan is a dense, compact, slowly permeable layer in the subsoil. [1] It has a much higher clay content than the overlying material, from which it is separated by a sharply defined boundary. The dense structure restricts root growth and water infiltration. Therefore, a perched water table might form on top of the claypan. [2]
Houdek (soil) A 4-foot (1.2 m) cross section of Houdek loam. Houdek is a type of soil composed of glacial till and decomposed organic matter. The soil series was established in 1955 in Spink County, South Dakota. [1] It is unique to the United States, but in particular to South Dakota where it is the state soil. Surface layer.
Soil scientists use the capital letters O, A, B, C, and E to identify the master horizons, and lowercase letters for distinctions of these horizons. Most soils have three major horizons—the surface horizon (A), the subsoil (B), and the substratum (C). Some soils have an organic horizon (O) on the surface, but this horizon can also be buried.
Topsoil is composed of mineral particles and organic matter and usually extends to a depth of 5-10 inches (13–25 cm). Together these make a substrate capable of holding water and air which encourages biological activity. There are generally a high concentration of roots in topsoil since this is where plants obtain most of their vital nutrients.
Pedology. Pedology (from Greek: πέδον, pedon, "soil"; and λόγος, logos, "study") is a discipline within soil science which focuses on understanding and characterizing soil formation, evolution, and the theoretical frameworks for modeling soil bodies, often in the context of the natural environment. [1] Pedology is often seen as one of ...
Alfisol. Alfisols are a soil order in USDA soil taxonomy. Alfisols form in semi-arid to humid areas, typically under a hardwood forest cover. They have a clay-enriched subsoil and relatively high native fertility. "Alf" refers to aluminium (Al) and iron (Fe). Because of their productivity and abundance, Alfisols represent one of the more ...