秸秆与牛粪还田配施氮素对砂姜黑土有机碳矿化及固持的影响OA

To elucidate the critical role of combined maize straw,cattle manure,and nitrogen application in regulating soil organic carbon(SOC)mineralization and stabilization in lime concretion black soil,an 80 d constant-temperature incubation experiment was conducted.A double-exponential model was applied to fit SOC mineralization dynamics under treatments of cattle manure(CD0),straw(CS0),and their combination(CC0)with or without nitrogen input.Nitrogen addition with straw-manure incorporation effectively alleviated microbial nitrogen limitation,enhanced microbial entropy(qMB),and stimulated early-stage carbon mineralization.Despite enhancing cumulative CO2-C release by the end of incubation,nitrogen addition did not deplete SOC content,which remained stable.Model analysis indicated that nitrogen-amended straw-manure treatment(NCC)sustained the highest proportion of recalcitrant carbon(63.9％)while maintaining the lowest decomposition rate(k2=0.001 d-1).Moreover,the potential mineralizable carbon pool(C1+C2)reached 4149.1 mg/kg,a 23.3％increase compared with the non-nitrogen control(CC).Relative to CC,NCC significantly increased the labile(C1)and recalcitrant(C2)pools by 28.8％and 137.9％(P＜0.05),respectively.These findings highlighted that the integrated application of cattle manure,straw,and nitrogen synergistically regulated microbial activity and carbon pool redistribution,suppressed turnover frequency,and promoted recalcitrant carbon accumulation.This strategy not only enhanced SOC stability,but also provided a sustainable pathway to reconcile agricultural productivity with long-term soil carbon sequestration.