不同化学结构外源碳添加对稻田土壤有机碳组分及碳排放的影响OA

Although exogenous carbon input is known to enhance carbon sequestration potential in paddy soils,the mechanisms by which its chemical structure influences soil carbon emissions and organic carbon(SOC)fractions remain unclear.In this study,we conducted an anaerobic slurry incubation experiment to compare the effects of adding non-structural carbon sources(glucose,starch)versus a structural carbon source(cellulose)on CO2 and CH4 emissions,as well as on labile(LOC)and recalcitrant(ROC)organic carbon,particulate organic carbon(POC)and mineral-associated organic carbon(MAOC).Results showed that SOC content in soils treated with exogenously added glucose,starch,and cellulose decreased by 1.33％,showed no significant effect,and increased by 3.24％,respectively,compared with the control.While all exogenous carbon additions significantly increased cumulative CO2 emissions by 69.71％-73.35％and CH4 emissions by 105.17％-117.56％,there were no significant differences among the treatments.LOC was positively correlated with SOC(r=0.711,p=0.010)and was significantly lower in glucose and starch treatments than in the cellulose treatment.Although ROC content did not differ significantly among exogenous carbon treatments,the w(ROC)/w(LOC)ratio was significantly higher in glucose and starch treatments than in the cellulose treatment,indicating that non-structural carbon inputs enhance the oxidative stability of SOC.Conversely,MAOC content was significantly lower in glucose and starch treatments than in the cellulose treatment,while dissolved organic carbon(DOC)and ferrous iron(Fe2+)concentrations showed opposite trends.This suggests that non-structural carbon inputs promote the reductive dissolution of Fe(Ⅲ)minerals,thereby weakening the mineral protection of SOC.Collectively,these findings demonstrate that the chemical structure of exogenous carbon regulates paddy SOC stocks primarily by modulating SOC oxidative stability and mineral-mediated protection mechanisms.