我国稻田甲烷排放的时空特征与减排途径

Spatiotemporal characteristics and reduction approaches of methane emissions from rice fields in China

  • 摘要: 水稻是我国第一大口粮作物, 甲烷(CH4)是全球第二大温室气体, 稻田CH4减排意义重大。本文基于国家统计数据和文献收集, 计算分析了我国2001—2018年水稻播种面积和单位产量CH4排放的时空特征, 并进一步总结了稻田CH4排放的关键过程及其主要影响因子。研究结果表明, 2001—2018年我国水稻总播种面积和稻田CH4总排放量呈先降低后升高再降低的趋势, 单位水稻产量CH4排放则呈整体下降趋势。稻田CH4排放包括土壤CH4产生、氧化与传输3个过程, 主要受水稻品种、土壤特性、气候条件、农艺措施等因素影响。受水稻播种面积影响, 我国稻田CH4排放量呈东南高西北低的特征, 单位产量CH4排放量呈南高北低的特征。基于上述分析, 本文提出选用低排放水稻品种、应用减排稻作技术、施用CH4减排产品等水稻栽培减排途径。同时, 针对我国稻田CH4排放的区域特征, 提出在选用高产低排放品种基础上, 南方平原稻作区重点应用好氧耕作与控水增氧等减排技术, 南方丘陵稻作区重点应用生物炭和石灰等减排产品, 北方稻作区重点应用好氧耕作和硫酸铵替代部分尿素等减排技术。最后, 本文还提出了促进稻田CH4减排的科技创新与政策创设建议, 以期为实现水稻丰产与稻田CH4减排的协同提供理论参考。

     

    Abstract: Rice is the main staple crop in China and methane (CH4) is the second most important greenhouse gas worldwide. Therefore, it is important to reduce CH4 emissions from paddy fields. Based on national statistical data and literature collection, we calculated and analyzed the spatial and temporal characteristics of CH4 emissions at the rice sown-area scale and yield scale in China from 2001 to 2018 and further summarized the key processes and main influencing factors of CH4 emissions. The results of this study showed that the total sown area of rice and area-scaled CH4 emissions from rice fields in China showed an overall trend of first decreasing, then increasing, then decreasing again from 2001 to 2018; however, yield-scaled CH4 emissions in all regions showed a decreasing trend. CH4 emissions from rice fields mainly included three processes of production, oxidation, and transport, which were mainly influenced by rice varieties, soil characteristics, climatic conditions, and agronomic measures. Owing to the influence of rice sown areas, area-scaled CH4 emissions from paddy fields in China were high in the southeast and low in the northwest, and yield-scaled CH4 emissions were high in the south and low in the north. Based on the above findings, this study suggested reducing CH4 emissions by applying a new rice cultivar, cropping mode, and products with high yield and low CH4 emissions. Given the regional characteristics of CH4 emissions in China, this study first proposed the selection of rice cultivars with high yield and low CH4 emissions and the application of aerobic dry tillage and water-control irrigation in the southern plain region, biochar and lime in the southern hilly region, and aerobic dry tillage and partially alternative urea with ammonium sulfate in the northern rice cropping region. Finally, some suggestions were put forward related to science, technology and policy innovations for CH4 emission reduction to provide important references for achieving the win-win target of high yield and low CH4 emissions.

     

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