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A diagnostic horizon is a horizon used to define soil taxonomic units (e.g., to define soil types). A taxonomic unit is determined by the presence or absence of one or more diagnostic horizons in a required depth.
This detritus or dead organic material and its constituent nutrients are added to the top layer of soil, commonly known as the litter layer or O horizon ("O" for "organic"). Litter is an important factor in ecosystem dynamics , as it is indicative of ecological productivity and may be useful in predicting regional nutrient cycling and soil ...
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.
Cutans are common features in soil and represent focuses of chemical and biological reactions. Cutans may include clay skins or coatings of silica, sesquioxide, manganese, ferromanganese, soil organic matter or carbonate. [3] Clay skins are also called argillans, and soil horizons with sufficient clay illuviation are termed argillic horizons.
A soil scientist examining horizons within a soil profile. Soil science is the study of soil as a natural resource on the surface of the Earth including soil formation, classification and mapping; physical, chemical, biological, and fertility properties of soils; and these properties in relation to the use and management of soils.
American soil scientist Hans Jenny published in 1941 [128] a state equation for the factors influencing soil formation: S = f(cl, o, r, p, t, ...) S soil formation; cl (sometimes c) climate; o organisms (soil microbiology, soil mesofauna, soil biology) r relief; p parent material; t time; This is often remembered with the mnemonic Clorpt.
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.
Soil biology is the study of microbial and faunal activity and ecology in soil. Soil life , soil biota , soil fauna , or edaphon is a collective term that encompasses all organisms that spend a significant portion of their life cycle within a soil profile, or at the soil- litter interface.