凋落物不同输入方式和深度对砂质土壤团聚体结构及有机碳组分的影响OA

To reveal the key mechanism by which soil aggregates affect and stabilize soil organic carbon(SOC)through their structural stability,this study used fresh litter and naturally decomposed litter(2-year decomposition)from Platanus orien-talis L.plantations as experimental materials,and conducted a two-factor,two-level completely randomized block experi-ment consisting of 9 plots(8 treatments plus a no-litter input control).Soil samples were collected after six months of treat-ment to determine soil aggregate indices,soil organic carbon and its fractions,as well as soil physicochemical properties.The least significant difference(LSD)method was employed to conduct significance analysis and multiple comparisons of the data.The results showed that there were significant differences in the effects of litter input patterns and litter types on soil aggregate stability and organic carbon fractions.Compared with the no-litter control(CK),the mixing application of decomposed litter with soil significantly enhanced the stability of topsoil aggregates,and increased their mean weight diam-eter(MWD)and geometric mean diameter(GMD).Litter addition generally increased the SOC content.However,its effects on different SOC fractions varied.The contents of coarse particulate organic carbon(CPOC)and fine particulate or-ganic carbon(FPOC)were significantly increased in multiple treatments,among which deep incorporation of decomposed litter exhibited a particularly prominent promotion effect on FPOC content.In contrast,there was no significant change in the content of mineral-associated organic carbon(MAOC).SOC content was positively correlated with soil aggregate stabil-ity,indicating that litter input promotes SOC accumulation by improving aggregate stability,and artificial regulation of lit-ter input patterns exerts a positive effect on both sandy soil structure improvement and SOC content enhancement.