In agriculture, humus is often used simply to mean mature compostA soil conditioning material of decomposing organic matter which provides nutrients and enhances soil structure. [bM 06/08, 02/09] More, or natural compostA soil conditioning material of decomposing organic matter which provides nutrients and enhances soil structure. [bM 06/08, 02/09] More extracted from a forest or other spontaneous source for use to amend soil.