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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 ...
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.
Soil formation, also known as pedogenesis, is the process of soil genesis as regulated by the effects of place, environment, and history. Biogeochemical processes act to both create and destroy order within soils.
There are 12 soil orders (the top hierarchical level) in soil taxonomy. [2] [3] The names of the orders end with the suffix -sol. The criteria for the different soil orders include properties that reflect major differences in the genesis of soils. [4] The orders are: Alfisol – soils with aluminium and iron.
Parent material is the underlying geological material (generally bedrock or a superficial or drift deposit) in which soil horizons form. Soils typically inherit a great deal of structure and minerals from their parent material, and, as such, are often classified based upon their contents of consolidated or unconsolidated mineral material that has undergone some degree of physical or chemical ...
Soil structure describes the arrangement of the solid parts of the soil and of the pore spaces located between them (Marshall & Holmes, 1979). [1] Aggregation is the result of the interaction of soil particles through rearrangement, flocculation and cementation.
A full geotechnical engineering soil description will also include other properties of the soil including color, in-situ moisture content, in-situ strength, and somewhat more detail about the material properties of the soil than is provided by the USCS code. The USCS and additional engineering description is standardized in ASTM D 2487. [4]
A fragipan is a diagnostic horizon in USDA soil taxonomy. They are altered subsurface soil layers that restrict water flow and root penetration. Fragipans are similar to a duripan in how they affect land-use limitations. In soil descriptions, they are commonly denoted by a Bx or Btx symbol. They often form in loess ground. [1]