Topic summary
Soil horizons
Extracted from the Wikipedia article Soil horizon.
Diagnostic soil horizons
Many soil classification systems have diagnostic horizons. 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. In addition, most classification systems use other soil characteristics to define taxonomic units. The diagnostic horizons need to be thoroughly characterized by a set of criteria. When allocating soil (a pedon, a soil profile) to a taxonomic unit, one has to check every horizon of this soil and decide whether or not the horizon fulfills the criteria of a diagnostic horizon. Based on the identified diagnostic horizons, one can proceed with the allocation of the soil to a taxonomic unit. The following lists the diagnostic horizons of two soil classification systems.