Term (Latin for soil) for the totality of the almost exclusively dead organic matter of a soil, which makes up the vast majority of the soil organic matter (OBS or SOM = Soil Organic Matter). However, about 5% of the soil organic matter also consists of living organic matter, i.e. all living animal (such as isopods, mites, caterpillars, earthworms, snails and spiders) and plant (such as algae, lichens and mosses) organisms, as well as microorganisms (such as bacteria and fungi). One teaspoon of humus contains 100 million bacteria, 60 kilometres of fungal filaments and 1,000 nematodes (threadworms). The living part of the organic soil substance is also called edaphon (Greek edaphos = soil).
Humus is mainly subject to the lively activity of the living soil organisms, which continuously contribute to the transformation (humification)...
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Egon Mark
Diplom-Sommelier, Weinakademiker und Weinberater, Volders (Österreich)