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A soil layer is a zone in the soil, approximately parallel to the soil surface, with properties different from layers above and/or below it. If at least one of these properties is the result of soil-forming processes, the layer is called a soil horizon. In the following, the term layer is used to indicate the possibility that soil-forming ...
Soil texture is determined by the relative proportion of the three kinds of soil mineral particles, called soil separates: sand, silt, and clay. At the next larger scale, soil structures called peds or more commonly soil aggregates are created from the soil separates when iron oxides , carbonates , clay, silica and humus , coat particles and ...
In soil classification systems, topsoil is known as the O Horizon or A Horizon. [8] [9] Soil horizons are layers parallel to the soil surface whose physical, chemical and biological characteristics differ from the layers above and beneath.
The mineral material from which a soil forms is called parent material. Rock, whether its origin is igneous, sedimentary, or metamorphic, is the source of all soil mineral materials and the origin of all plant nutrients with the exceptions of nitrogen, hydrogen and carbon.
In soil science, agriculture and gardening, hardpan or soil pan is a dense layer of soil, usually found below the uppermost topsoil layer. [1] There are different types of hardpan, all sharing the general characteristic of being a distinct soil layer that is largely impervious to water. Some hardpans are formed by deposits in the soil that fuse ...
A further consequence of continued cultivation and traffic is the development of compacted, impermeable layers or 'pans' within the profile. The decline of soil structure under irrigation is usually related to the breakdown of aggregates and dispersion of clay material as a result of rapid wetting.
Subsoil layer. 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.
A stonelayer, or soil stonelayer, or stone line, is a three-dimensional subsurface layer, or soil horizon, dominated by coarse particles (>2mm), that generally follows (mimics) the surface topography (Sharpe 1938).