不同绿肥秸秆还田对玉米根系及土壤有机碳的影响OA

Against the backdrop of global climate change and the green transition in agriculture,enhancing the carbon sequestration capacity of farmland soils has emerged as a crucial strategy for achieving the"dual carbon"goals.Red soil drylands in southern China are commonly plagued by issues such as soil acidification,structural compaction,low fertility,and substantial loss of soil organic carbon,which severely constrain regional agricultural sustainable development and the functioning of soil carbon sinks.There is an urgent need to explore ecological cultivation measures that can simultaneously improve soil fertility and enhance carbon sequestration capacity.In this study,a pot experiment was conducted with five treatments:straw returning of Chinese milk vetch,winter vetch,common vetch,and their mixture,and a control treatment with no straw returning.The experiment focused on investigating the effects of green manure straw returning on maize root growth and soil active organic carbon fractions in red soil drylands.The results indicated that compared with the control,the winter vetch straw treatment significantly increased maize belowground dry weight by 171％and the root-shoot ratio by 165％;the mixed straw treatment significantly increased the total root surface area and root volume by 58％and 102％,respectively;the common vetch and mixed straw returning treatments significantly reduced root fineness,with the roots tending to become robust and short.With respect to soil active organic carbon fractions,green manure straw returning(excluding the common vetch straw returning treatment)significantly increased the content of hot water-soluble organic carbon(HWSOC),with the winter vetch straw treatment yielding a 49％increase,and significantly decreased the content of dissolved organic carbon(DOC),with the mixed straw treatment resulting in a 50％decrease.However,no significant variation was observed in microbial biomass carbon(MBC)across treatments.Additionally,the study revealed that alterations in root morphology were closely correlated with the dynamics of DOC in soil.Root fineness exhibited a significant positive correlation with soil DOC content,while total root volume and average root diameter showed significant negative correlations with DOC content.In conclusion,green manure straw and roots synergistically enhance the transformation and sequestration of labile organic carbon pools in red soil.Among the treatments,the winter vetch straw returning and mixed straw returning modes exhibited superior effects.These findings can provide a theoretical foundation for promoting ecological agriculture characterized by root-driven carbon sequestration in the red soil drylands of southern China and hold significant practical implications for achieving the synergistic development of agricultural carbon sequestration,emission reduction,and soil fertility improvement.It is recommended that further validation should be conducted under field conditions in the future,combined with in-depth research on microbial mechanisms.