Humus (Topical Term)

Dunster, J. Dict. of natural resource management, c1996 (humus: in the narrow sense, humus is amorphous organic material (plant or animal) that has decayed beyond the point of recognition, and lies beneath the litter layer and above the mineral soil. A rich component of soil containing humic and fulvic acids, humus forms the main organic layer on the forest floor, but can also be found in water. In the broader sense, humus may refer to the whole forest floor and organic matter within the mineral soil.)

The dict. of forestry, c1998 (humus: black or brown organic material of complex composition which is the end-product of microbial breakdown of plant and animal residues at the soil surface --synonym soil organic matter)