土壤有机质概念和分组技术研究进展

土壤有机质一直是土壤学研究领域的重点，在过去的50年里，对土壤质量可持续性观念的增强和寻找快速判断人为因素对土壤质量影响方向指标的强烈愿望导致了土壤有机质的研究重点发生了急剧变化：对农业措施反映慢的土壤腐殖质类物质的研究正在退出土壤有机质研究领域，而侧重点逐渐转向了土壤中未受微生物作用或正在受微生物降解的有机残体；也出现了新的土壤有机质研究概念和对应测试手段：土壤有机质的比重分组、与有机质结合的土壤颗粒大小分组、土壤团聚体中的POM和iPOM以及土壤水溶性有机质和微生物体C等概念和测试手段被相继提了出来，土壤有机质的研究重点正在从土壤微生物的作用产物(腐殖质)向土壤微生物作用前的、具有部分生物活性的有机质(轻组有机质、砂粒组和粗粉砂粒组中的有机质、POM和iPOM)和完全具有生物活性的有机质(微生物体C和水溶性有机质)转移，这一过程与土壤有机质概念的拓展密不可分。

Concepts and relative analytical techniques of soil organic matter

The research of soil organic matter (SOM) has been highlighted in soil science.In the past 50 years,new perspectives in the relationship between SOM and sustainability of atmosphere and biomosphere,and strong motivation to find a vivid index for soil quality variation induced the transformation in concepts and analytical techniques of SOM:the curiousness to humic substances faded off since they were dull to anthropogenic activities,and interests were focused on the light fraction of organic matter (LFOM),organic carbon associated with different mineral particles in size,particulate and intra-particulate organic matter (POM and iPOM),water soluble organic matter (WSOM),and microbial biomass carbon (MB-C).The relative fractionation procedures have been developed,and the main research activities on SOM are transformed from the products of microorganisms (humus) to the organic matter comprised in plant residues at their various decomposition stages and the organic carbon in microorganisms,since they are biologically active and immediately respond to soil cultivation and tillage,crop rotation,and fertilizer application,etc.