第二章土壤有机质SoilOrganicMatter（SOM）,第一节土壤有机质的来源、含量及其组成第二节土壤有机质的分解和转化第三节土壤腐殖物质的形成和性质第四节土壤有机质的作用和管理,第一节土壤有机质的来源、含量及其组成一、土壤有机质的来源,Soilorganicmatterisderivedfromanumberofsources(Fig.),ofwhichthemostimportantisplantlitter.Thisconsistsofavarietyofplantdebrisincludingleaves,stems,flowers,twigs,bark,andthelargebranchesandtrunksoftrees.,Othersoilorganiccomponentsincludesoilorganicmatter,plantroots,rootexudates,soilorganismstogetherwiththeirfaecalremainsandmetabolites,andorganicsubstanceswashedintothesoilfromv
