炉渣与生物炭混施对稻田土壤碳固定与温室气体排放的影响机制

Accumulation of soil carbon and reduction of greenhouse gases in paddy filed are crucial both for sustainability of rice production and for potential mitigation of global climate warming. In recent years, there are some reports concerning the application of industrial and agricultural wastes on soil carbon sequestration and greenhouse gas emissions reduction, however, its mechanism study is still very lack. We carry out the study of the effect of slag and biochar mixed application on paddy field soil carbon sequestration and greenhouse gas emissions and its mechanism with the combination of the in situ slag and biochar mixed application and laboratory simulation experiments using molecular technique, 13C-NMR technique, microplate reader technique, and the physical and chemical classification methods in red soil paddy field. Specifically, this project attempts to reveal the contribution of physical protection, chemical binding as well as microbial action mechanism of soil carbon sequestration in various soil depths and temporal scales, to clarify the sustained effect, and microbial and enzymological mechanisms on greenhouse gas emissions, and to discriminate intrinsic link between soil carbon sequestration and greenhouse gas emissions under the slag and biochar mixed application. The research will offer sound basis to understanding the role of rice agriculture in soil carbon sequestration and reduction potential, for developing and improving the carbon cycling theory of cropland soils of China. Furthermore, this research will provide the scientific basis for selection the adaptation and mitigation countermeasures of greenhouse gas of rice agriculture.

稻田土壤碳积聚和温室气体减排在维持稻米的可持续生产与减缓全球气候变暖中具有重要意义。近年来，工农业废弃物在稻田土壤固碳与温室气体减排中的应用虽已有一些报道，但其机制研究仍十分薄弱。本项目以红壤稻田为研究对象，采用野外炉渣与生物炭混施处理试验与室内模拟实验相结合，利用分子生物学技术、13C-NMR技术、酶标仪技术、物理与化学分组方法，研究炉渣与生物炭混施对稻田土壤碳固定与温室气体排放的影响机制，特别是其中炉渣与生物炭混施条件下，揭示不同土层和时间尺度土壤碳固定的物理保护、化学结合与稳定、微生物作用机制的贡献，阐明炉渣与生物炭混施对稻田温室气体排放影响的持续效应及其微生物与酶学机制，辨析土壤固碳与温室气体排放变化的内在联系，为了解我国稻作农业发展中稻田固碳与减排能力的可能演变趋势，为发展和完善我国农田土壤碳循环理论奠定科学积累，并进一步为稻作农业温室气体减排的途径和措施的选择提供科学依据。

稻田土壤碳积聚和温室气体减排在维持稻米的可持续生产与减缓全球气候变暖中具有重要意义。近年来，工农业废弃物在稻田土壤固碳与温室气体减排中的应用虽已有一些报道，但其机制研究仍十分薄弱。本项目以红壤稻田为研究对象，采用野外炉渣与生物炭混施处理试验与室内模拟实验相结合，利用分子生物学技术、13C-NMR技术、酶标仪技术、物理与化学分组方法，研究炉渣与生物炭混施对稻田土壤碳固定与温室气体排放的影响机制，特别是其中炉渣与生物炭混施条件下，揭示不同土层和时间尺度土壤碳固定的物理保护、化学结合与稳定、微生物作用机制的贡献，阐明炉渣与生物炭混施对稻田温室气体排放影响的持续效应及其微生物学机制。研究结果表明，施加处理均能够增加土壤碳库储量；施加处理能够增加土壤有机碳含量，并且能够在接下去的几年均能够增加有机碳含量。施加处理抑制了土壤有机碳的矿化，各施加处理下土壤有机碳矿化速率均表现为犁耕层高于非犁耕层。水稳定性大团聚体数量随深度增加而增加，土壤团聚体的稳定性随土层加深而增强。炉渣与生物炭施加处理当年度，降低了土壤细菌、真菌的数量；2年之后则增加了土壤中细菌真菌的数量。施加处理均会改变土壤细菌、真菌的群落结构，并对其优势菌属的丰度产生影响，从而对土壤碳组分产生影响，并且对温室气体的排放产生影响。通过对温室气体4年排放通量的测定可以发现，施加处理均能够降低土壤中CO2和CH4的排放；而N2O 不同年份表现出来的结果不一致，具有较大的波动性。