Humic Substances

**Definition:** Organic matter in a state of advanced decay, after passing through the stages of COMPOST and PEAT and before becoming lignite (COAL). It is composed of a heterogenous mixture of compounds including phenolic radicals and acids that polymerize and are not easily separated nor analyzed. (E.A. Ghabbour & G. Davies, eds. Humic Substances, 2001).

**Tree numbers:** - D02.241.444 - D02.455.426.559.389.657.377 - D20.721.500

**Synonyms:** - Humic Substance