土壤有机质是指土壤中含碳的有机化合物,通常分为腐殖质和非腐殖质。其来源包括四个方面:一是植物残体,包括各类植物的凋落物、死亡的植物体及根系,这是自然状态下土壤有机质的主要来源,对森林土壤尤为重要。二是动物、微生物残体,包括土壤动物和非土壤动物的残体,及各种微生物的残体,这部分来源相对较少,但对原始土壤来说,微生物是土壤有机质的最早来源。三是排泄物和分泌物,这部分来源虽然量很少,但对土壤有机质的转化起着非常重要的 Soil organic matter refers to organic compounds containing carbon in the soil, usually divided into humus and non-humus. Its origins include four aspects: First, plant debris, including litter of various types of plants, dead plants and roots, which is the main source of soil organic matter in the natural state, is particularly important for forest soils. Second, animal and microbial remains, including the residues of soil animals and non-soil animals, and the residues of various microorganisms are relatively few in origin. However, for primitive soil, microbes are the earliest source of soil organic matter. Third, excrement and secretions, although this part of the source is small, but the conversion of soil organic matter plays a very important