秸秆还田下外源物料添加对川南冬闲稻田秸秆腐解及温室气体排放的影响OA

To investigate the effects of adding different exogenous amendments on straw decomposition and greenhouse gas(GHG)emissions in winter-fallow paddy fields under straw returning in the southern Sichuan,a field experiment was conducted in Yibin City,Sichuan Province.Four treatments were set up:straw returning(CK,A0N0);straw returning+nitrogen fertilizer(A0N1);straw returning+microbial agent(A1N0);straw return+microbial agent+nitrogen fertilizer(A1N1).A split-plot experimental design was adopted to systematically measure straw decomposition rates and emission fluxes of methane(CH4),nitrous oxide(N2O),and carbon dioxide(CO2).Results showed that the decomposition rate of CK during the winter-fallow period was significantly lower than that of treatments with combined application of microbial agent and N fertilizer.Among all treatments,the single application of microbial agent achieved the highest decomposition rate in the early stage,reaching 65.08%.Compared with CK,both microbial agent and N fertilizer applications increased the straw decomposition rate,although the rate decreased in the later decomposition stage.The GHG emission fluxes across all treatments exhibited a"U-shaped"dynamic pattern during the winter-fallow period(high in the early stage,low in the middle,and rebounding in the late stage).N fertilizer application significantly enhanced CH4 emissions in the early stage of straw return,while the combined application of microbial agent and N fertilizer reduced CO2 emissions by 59.81%.N2O emissions remained at relatively low levels throughout the winter-fallow period.In terms of global warming potential(GWP),the treatment with sole N fertilizer application had the highest GWP(3,082.50 kg/hm2),whereas the treatment with combined microbial agent and N fertilizer had the lowest GWP(1,924.80 kg/hm2).CO2 contributed most to the total GWP,accounting for 56.65%-75.20%across all treatments.In conclusion,applying a combination of decomposing microbial agent and N fertilizer during straw return in winter-fallow paddy fields of southern Sichuan can not only accelerate straw decomposition but also significantly reduce the overall GHG warming potential,providing important scientific evidence and technical support for green production and improved field management of regional winter-fallow paddy systems.