Meaning of A-HORIZON in English
The uppermost zone in the Soil Profile, from which soluble Salts and Colloids are leached, and in which organic matter has accumulated. Generally this represents the most fertile soil layer. Along with the B-Horizon, this layer constitutes part of the Zone of Eluviation.
Environmental engineering English vocabulary. Английский словарь экологического инжиниринга. 2012