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Feb 17, 2023 · Soil Horizons. The soil is the topmost layer of the earth’s crust consisting of air, water, inorganic minerals (rock, sand, clay, and slit), and organic matter (dead plants and animals). It forms the source of food for plants. It provides shelter for many animals such as insects, centipedes, burrowing animals, microorganisms, and many others.
All these properties are used to define types of soil horizons. 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 ...
The horizon description system begins by splitting soil horizons into two distinct groups: organic and mineral horizons. Organic horizons are those that contain 17% or more organic carbon; mineral horizons have less than 17% organic carbon. The major symbols used in describing mineral soil layers in Canada are shown in the following tables.
These are called transitional horizons, and indicated by two capital letters like AB or BA. The first of the two is the more dominant of the two processes. A similar-looking notation but with an added /, like E/B or B/E mean that there are distinct areas of each in the layer rather than a smooth transition.
The start and end of the A and B horizons as measured from the soil surface. For example, if there is an LFH layer on top of your mineral soil that is 5 cm thick, you would record it as LFH 5-0 cm. The A soil horizon then starts at 0 cm below the surface and ends at 11 cm, and this depth will be recorded as 0-11 cm.
The genetic relationships of soil horizons are important for an understanding of pedogenesis and soil management. Soil scientists are trained to primarily look along a vertical transect for horizons that parallel the soil surface (Muir, 1962), and thus most soil scientists preferentially identify and describe regions parallel to the soil ...
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The surface mineral and/or organic layer of the earth that has experienced some degree of physical, biological and chemical weathering. Soils are limited natural resources. They are considered renewable because they are constantly forming. Though this is true, their formation occurs at extremely slow rates.
