In ABC soil, the uppermost, darkest zone that is rich in organic matter. Also called zone of eluviation, zone of leaching.
(Physical Geography) the top layer of a soil profile, usually dark-coloured and containing humus and from which soluble salts may have been leached. See B horizon
, C horizon
the topsoil in a soil profile.
|Noun||1.||A horizon - the top layer of a soil profile; usually contains humus|humus
- partially decomposed organic matter; the organic component of soil