humusa

Humusa is a term encountered in ecological discourse and soil science discussions to denote a proposed form of organic matter in soils that combines humus-like characteristics with enhanced structural and nutrient-cycling roles. The term is not part of formal soil taxonomy and has no single, universally accepted definition. In use, it often serves as a heuristic to discuss complex organic matter dynamics beyond classic humus concepts.

In some accounts, humusa is described as an evolved or augmented layer of persistent organic matter resulting from intensified plant inputs and microbial activity, forming a cohesive, microbially stabilized matrix within mineral soil that interacts closely with mineral surfaces.

Proposed properties include greater stability, resistance to decomposition, and stronger associations with minerals and microbial networks, which can enhance soil aggregation, water retention, and nutrient exchange capacity. The concept highlights the active role of soil biota in transforming and stabilizing organic matter, rather than treating humus as a passive residue.

Status and use: Because there is no standardized definition or measurement protocol, humusa remains mainly within speculative discussions, niche research, or popular science discussions. It is sometimes invoked in discussions of management practices intended to boost organic-matter stability, such as diversified cropping, reduced tillage, and biochar, but evidence is tentative.

See also: Humus, Soil organic matter, Carbon sequestration, Soil biology.