Definitions for "A horizon"
Keywords:  humus, horizon, eluviation, humic, situ
The soil horizon below the O horizon and above the B horizon . In this layer, humus and other organic materials are mixed with mineral particles, while finer particles and soluble substances are washed out.
Mineral horizon formed at or near the surface in the zone of leaching and eluviation of materials in solution or suspension or of maximum in situ accumulation of organic matter. Distinguishing characteristics usually designated by a subscript e.g. Ah - humic( organic matter rich) horizon
The surface soil. See Soil Horizon.
Keywords:  topsoil
Topsoil