祝贞科, 肖谋良, 魏亮, 王双, 丁济娜, 陈剑平, 葛体达. 稻田土壤固碳关键过程的生物地球化学机制及其碳中和对策[J]. 中国生态农业学报 (中英文), 2022, 30(4): 592−602. DOI: 10.12357/cjea.20210748
引用本文: 祝贞科, 肖谋良, 魏亮, 王双, 丁济娜, 陈剑平, 葛体达. 稻田土壤固碳关键过程的生物地球化学机制及其碳中和对策[J]. 中国生态农业学报 (中英文), 2022, 30(4): 592−602. DOI: 10.12357/cjea.20210748
ZHU Z K, XIAO M L, WEI L, WANG S, DING J N, CHEN J P, GE T D. Key biogeochemical processes of carbon sequestration in paddy soil and its countermeasures for carbon neutrality[J]. Chinese Journal of Eco-Agriculture, 2022, 30(4): 592−602. DOI: 10.12357/cjea.20210748
Citation: ZHU Z K, XIAO M L, WEI L, WANG S, DING J N, CHEN J P, GE T D. Key biogeochemical processes of carbon sequestration in paddy soil and its countermeasures for carbon neutrality[J]. Chinese Journal of Eco-Agriculture, 2022, 30(4): 592−602. DOI: 10.12357/cjea.20210748

稻田土壤固碳关键过程的生物地球化学机制及其碳中和对策

Key biogeochemical processes of carbon sequestration in paddy soil and its countermeasures for carbon neutrality

  • 摘要: 稻田生态系统具有碳源和碳汇双重功能, 调控稻田土壤固碳减排, 对于保障我国粮食安全以及实现“碳中和”目标具有重要意义。近年来, 国内外学者在稻田土壤有机碳周转过程与机制方面开展了大量研究, 本文从土壤有机碳的来源、转化、稳定与技术调控等方面, 总结和分析稻田土壤固碳过程和机制, 并提出应对“碳中和”的策略。稻田土壤有机碳主要来源于水稻秸秆、根系、根际沉积碳、微生物同化碳以及有机肥等。外源有机碳输入土壤后, 其分解矿化过程首先受控于有机碳溶出过程, 而微生物矿化溶出的有机碳过程与土壤水分条件、养分含量及其计量比、微生物活性等因素密切相关。除了矿化释放的有机碳, 其余部分主要是通过微生物的同化代谢, 形成活体微生物及其残留物, 最终以团聚体保护、矿物结合态保护、微生物残体保护等形式固持于土壤中。我国水稻土具有显著的固碳效应, 近40年来的实测数据表明, 在水肥管理和秸秆还田等多举措实施下, 我国亚热带水稻土耕作层有机碳含量增加了约60%。采用增碳减排措施, 优化稻作系统耕作方式和田间管理模式, 建立碳减排生态补偿机制, 推动稻作系统纳入“碳交易”市场, 对实现“碳中和”起到了积极作用。所以, 在今后的研究中, 需要深入阐明稻田固碳功能形成机制, 提升核算与预测稻田碳中和能力, 加快稻田碳中和技术研发, 为提前实现“碳中和”战略目标提供科技支撑。

     

    Abstract: Rice field ecosystems have dual functions as C sources and C sinks. Soil C sequestration plays an important role in improving the productivity of rice fields, and greenhouse gas emissions from rice fields exacerbate the risk of global warming. Therefore, regulating the C sequestration and emission reduction of paddy soil is of great significance for ensuring food security in China and achieving the goal of “carbon neutrality”. In recent years, researches have focused on the processes and mechanisms of soil organic C (SOC) turnover in paddy fields worldwide. This review summarized the processes and mechanisms of soil C sequestration in paddy fields from the perspectives of sources, transformation, stabilization, and regulation techniques of SOC, and proposed strategies to deal with “carbon neutrality”. SOC is mainly derived from plants and microorganisms. The input of rice rhizosphere C accounted for approximately 28% of the entire underground C input during a single season, and the contribution rates of rice rhizosphere C and microbial assimilated C to the accumulation of SOC were 71.9% and 55.5%, respectively, which were much higher than that of rice straw (12.1%) and the root system (19.8%). After the input of exogenous organic materials into the soil, the decomposition and mineralization of organic materials were first controlled by the dissolution process of SOC, which was the rate-limiting step. The microbial mineralization of the dissolved SOC was affected by the soil moisture conditions, nutrients contents, stoichiometric ratio, microbial activity, and other factors. Apart from the emitted SOC, the remaining inputs were mainly anabolized to form living microorganisms and microbial residues, which were finally fixed in the soil protected by aggregates, organo-mineral colloidal complexes, and necromass (amino sugars). Based on the estimation of assimilation and emission of carbon dioxide, the annual net C sequestration of paddy ecosystems was approximately 156.4 Tg C in China, which proved that paddy soil had a significant C sequestration effect. Although straw removal or incineration, positive priming effects, and other factors decreased the amount of C sequestered in paddy soil, research data had shown that the SOC content of subtropical paddy soil had increased by 60% under the implementation of multiple management strategies such as irrigation and fertilizer application and straw returning in the last 40 years. It had a positive effect on achieving “carbon neutrality” by adopting the management of increasing C sequestration and mitigating greenhouse gas emissions. These management strategies included optimizing the combination of irrigation and fertilizer application and straw returning, establishing an ecological compensation mechanism for C emission reduction, and promoting the inclusion of the rice farming system in the “C trading market”. Therefore, it is necessary to clarify the mechanism of C sequestration in paddy fields, improve the accuracy of estimating and forecasting C neutrality, and accelerate the development of C neutralization technology in paddy fields in future research, which will provide scientific and technological support for achieving the “carbon neutrality” strategic goal in advance.

     

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