土壤有机质在土壤肥力中具有多方面的作用。首先,它是植物养分的来源。我国主要土壤表土中大约80—97%的氮、20—76%的磷[1,2]、38—94%的硫即以有机态存在。在有机质分解过程中,这些养分将逐步释出供植物吸收利用。其次,有机质能够改善土壤的结构和物理化学性质(缓冲性能,吸附、离子交换性能和络合能力等),为植物生长提供一个较好的土壤物理环境 Soil organic matter plays a multifaceted role in soil fertility. First, it is a source of plant nutrients. About 80-97% of nitrogen, 20-76% of phosphorus [1,2] and 38-94% of sulfur in the topsoil of our country are in organic form. In the decomposition of organic matter, these nutrients will be gradually released for plant absorption and utilization. Second, the organic matter can improve the structure and physicochemical properties of the soil (buffer properties, adsorption, ion exchange properties and complexing ability, etc.), provide a better soil physical environment for plant growth