秸秆直接还田与炭化还田下土壤有机碳稳定性和温室气体排放潜力的对比研究

Comparison of Soil Organic Carbon Stability and Greenhouse Gas Emissions Potential under Straw or Straw-derived Biochar Amendment

选取北方旱地和南方水田两种不同农业利用方式的土壤为研究对象,分别在旱地和水田设置了无秸秆还田(NR)、秸秆直接还田(SR)和秸秆转化为生物质炭还田(BR)三种处理,在作物收获后,采集对应处理的土壤通过室内培养对比研究了秸秆直接还田和生物质炭还田下土壤有机碳的稳定性及温室气体排放潜力的变化。研究结果表明:秸秆直接还田与生物质炭还田均可显著增加土壤有机碳和全氮含量,但不同处理下的土壤有机碳稳定性存在显著差异。从有机碳的矿化量和矿化率来看,生物质炭还田处理与秸秆直接还田处理相比,分别降低旱地、水田土壤矿化量的36.0%、21.5%和矿化率的47.0%、34.7%;水田与旱地相比,表观上水田矿化显著高于旱地土壤,但从土壤有机碳矿化率来看,水田土壤各处理均显著低于旱地土壤相同处理的19.0%、26.2%和9.2%。不同处理显著影响土壤N2O的释放,无论旱地还是水田土壤,与秸秆直接还田相比,施用生物质炭均显著降低土壤N2O的释放;进一步分析土壤产生的综合温室效应(GWP)表明,生物质炭还田下的GWP比秸秆直接还田显著降低39.6%和28.5%。因此,秸秆转化为生物质炭后还田可作为一项重要的农田土壤固碳减排措施进行秸秆利用。

In this study,three different treatments,including no straw return（NR）,straw return（SR） and biochar return（BR）,respectively,to dryland and paddy soil,were set up.After the crop was harvested,the soil sample in each treatment was collected for incubation in laboratory at constant temperature and moisture.The study compared the stability of soil organic carbon（SOC） and the emission potential of greenhouse gases between straw and biochar amendment in order to provide theoretical basis for straw resource utilization and agricultural soil carbon sequestration.The results showed there was a significantly increase in SOC and total nitrogen（N） content under straw and biochar amendments.But there were significant differences in SOC stability between different treatments.Compared to straw amendment,the SOC mineralization decreased by 36.0%,21.5% and mineralization rate of SOC decreased by 47.0% and 34.7%,respectively,under biochar amendments to dryland and paddy soils.Compared with dryland,the SOC mineralization in paddy field increased significantly,but the mineralization rates of SOC were significantly decreased by 19.0%,26.2% and 9.2% for the same treatment.There was a significant difference in N2O emissions between different treatments.Whether it was dryland or paddy,biochar amendments also reduced the N2O emissions significantly during the incubation process compared to straw amendments to soils.Further analysis showed the soil greenhouse effect was significantly reduced by 39.6% and 28.5% under biochar amendment than straw incorporation.Therefore,it could be a potential approach to return crop straw to soil by conversion of them to biochar.