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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.
The fertile Alfisols were most likely formed by Devonian forests. The oldest of the Alfisol paleosol forest soils are in the paleosols of the Aztec Siltstone in Victoria Land , Antarctica. In the paleosols of the Aztec Siltstone, the Rosemary paleosol, there is evidence for trees from surficial tree-throwing structures and large drab-haloed ...
Chernozem (/ ˈ tʃ ɜːr n ə z ɛ m / CHUR-nə-zem), [a] also called black soil, regur soil or black cotton soil, is a black-colored soil containing a high percentage of humus [3] (4% to 16%) and high percentages of phosphorus and ammonia compounds. [4] Chernozem is very fertile soil and can produce high agricultural yields with its high ...
Mollisol is a soil type which has deep, high organic matter, nutrient-enriched surface soil (), typically between 60 and 80 cm (24-31 in) in depth.This fertile surface horizon, called a mollic epipedon, is the defining diagnostic feature of Mollisols.
Because they are generally quite young, andisols typically are very fertile except in cases where phosphorus is easily fixed (this sometimes occurs in the tropics). They can usually support intensive cropping, with areas used for wet rice in Java supporting some of the densest populations in the world.
Much of the fertile agricultural soils of the Nile valley in Egypt are Entisols developed on alluvial materials (soil suborders Fluvent and Aquent) Entisols are soils, as defined under USDA soil taxonomy, that do not show any profile development other than an A-horizon (or “A” horizon). Entisols have no diagnostic horizons, and are ...
Nutrients in the soil are taken up by the plant through its roots, and in particular its root hairs.To be taken up by a plant, a nutrient element must be located near the root surface; however, the supply of nutrients in contact with the root is rapidly depleted within a distance of ca. 2 mm. [14] There are three basic mechanisms whereby nutrient ions dissolved in the soil solution are brought ...
A combination of nearly level to gently rolling glaciated till plains and hilly loess plains, average annual precipitation of 26–37 inches, which occurs mainly in the growing season, and fertile, warm, moist soils make this one of the most productive areas of corn and soybeans in the world.