长江中下游水稻生产固碳减排关键影响因素及技术体系

Key influencing factors and technical system of carbon sequestration and emission reduction in rice production in the middle and lower reaches of the Yangtze River

  • 摘要: 水稻生产是中国农业温室气体的主要排放源之一, 针对“碳达峰”和“碳中和”的战略目标, 探究影响水稻生产固碳减排的关键因素, 构建水稻生产固碳减排技术体系具有重要意义。 本文针对长江中下游水稻主产区, 开展包括免耕、氮肥深施、间歇性节水灌溉、秸秆氮肥配施管理等低碳管理措施在内的定位试验, 分析水稻生产固碳减排的关键影响因素。在长期监测稻田温室气体排放的基础上, 使用13C核磁共振技术分析有机碳官能团分子结构, 明确稻作管理措施增汇减排机理。进一步从碳足迹角度评估不同稻作管理技术下稻田生产间接碳排放。同时使用13C秸秆示踪技术, 明确秸秆外源碳在稻作循环中的转化比例。研究结果显示, 通过调控秸秆和氮肥配比, 可以促进秸秆碳向小分子官能团的转化, 并促进土壤团聚体吸附外源颗粒有机碳, 相比常规秸秆管理模式提高土壤碳库闭蓄态颗粒有机碳储量32.3%。间歇性节水灌溉技术可以通过提高甲烷氧化菌丰度, 减少稻田甲烷排放19.9%~21.1%。免耕等低能耗稻田管理技术可以减少燃油和人力等投入, 综合降低稻田生产间接碳排放10.5%~16.7%。相对于常规稻田秸秆还田模式, 间歇性节水灌溉、秸秆氮肥配施等管理技术可以提高秸秆外源碳循环固定率57.3%~59.9%。土壤团聚体结构发育、碳排放功能微生物、土壤氮素底物浓度、水稻生产碳足迹和作物碳固定量是影响水稻生产碳中和的关键因素。从“增汇” “减排” “降耗” “循环”角度, 构建水稻生产固碳减排技术体系可以促进水稻生产碳固持28.9%~67.6%。

     

    Abstract: Rice production is one of the main sources of greenhouse gas (GHG) emissions in China. Aiming at the strategic goals of “carbon peak” and “carbon neutrality,” it is of great significance to explore the key affecting factors and construct a technical system of carbon sequestration and emission reduction in rice production. Aimed at the main rice-producing areas in the middle and lower reaches of the Yangtze River, we conducted positioning experiments, including low-carbon management measures such as no-tillage, deep placement of nitrogen fertilizer, intermittent water-saving irrigation, and combined management of straw and nitrogen fertilizer, to analyze the key influencing factors of carbon sequestration and emission reduction in rice production. Based on a long-term monitoring of GHG emissions from rice fields, we used 13C nuclear magnetic resonance technology to analyze the molecular structure of organic carbon functional groups and clarified the mechanism of rice management measures for reducing carbon emissions and increasing carbon sinks. We further evaluated the indirect carbon emissions from rice production under different rice management technologies using the carbon footprint, and clarify the conversion ratio of exogenous straw carbon in rice systems using 13C-labeled straw carbon tracing technique. The results of this study showed that regulating the ratio of straw and nitrogen fertilizer could promote the conversion of straw carbon into small molecular functional groups, promote the adsorption of exogenous particulate organic carbon from soil aggregates, and increase the content of intra-aggregate particulate organic carbon by 32.3% in the soil carbon pool compared with those of conventional straw management methods. Intermittent water-saving irrigation technology could reduce methane emissions by 19.9%–21.1% in paddy fields by increasing the abundance of methane-oxidizing bacteria. Low-energy rice field management technologies, such as no-tillage, could reduce fuel and manpower inputs and comprehensively reduce indirect carbon emissions from rice production by 10.5%–16.7%. Compared with the conventional rice straw return mode, management techniques such as intermittent water-saving irrigation and combined straw and nitrogen fertilizer application could increase the exogenous carbon cycle sequestration rate of straw by 57.3%–59.9%. The development of soil aggregate structure, carbon emission functional microorganisms, soil nitrogen substrate concentration, rice production carbon footprint, and crop carbon sequestration are key factors that affect the carbon neutrality of rice production. Establishing a technical system of carbon sequestration and emission reduction from the perspectives of “sinks increase” “emission reduction” “consumption reduction” and “recycling” could promote rice production carbon neutrality by 28.9%–67.6%.

     

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