Humusica 1, article 4 : Terrestrial humus systems and forms-Specific terms and diagnostic horizons

Knowledge of a little number of specific terms is necessary to investigate and describe humipedons. This "new vocabulary" allows individuating and circumscribing particular diagnostic horizons, which are the fundamental bricks of the humipedon. Few "components" defined by specific terms characterize a specific "humipedon horizon"; few "humipedon horizons" compose a given "humus form" and some similar "humus forms" are grouped in a functional "humus system". In this article, specific terms and humus horizons are listed and explained one by one. Field difficulties are illustrated and resolved. The aim of the article is to present in a manner as simple as possible how to distinguish in the field the soil structures allowing a morpho-functional classification of terrestrial (aerated, not submerged) humipedons