水稻秸秆生物炭对南方稻田土壤的固碳减排效应

陈立天; 刘玉学; 何莉莉; 吕豪豪; 汪玉瑛; 杨生茂

doi:10.19336/j.cnki.trtb.2023041802

水稻秸秆生物炭对南方稻田土壤的固碳减排效应

Effects of Rice Straw Biochar on Soil Carbon Sequestration and Emission Reduction in Southern Paddy Fields

摘要

摘要:
目的研究不同生物炭添加量对稻田土壤固碳和温室气体减排的影响，以期为稻田生态系统固碳减排提供理论依据和技术支撑。
方法以南方稻田土壤为研究对象，在常规施肥条件下设置4个水稻秸秆生物炭添加量，分别为0、7.5、15.0和22.5 t hm⁻²，以不施肥且不添加生物炭为空白对照，对土壤理化性质、土壤固碳量、温室气体排放以及水稻产量进行测定，评估其净增温潜势和温室气体排放强度。
结果与常规施肥但不添加生物炭处理相比，添加22.5 t hm⁻²水稻秸秆生物炭显著降低稻田土壤容重达5.1%，显著提高土壤pH、全氮、有效磷和速效钾分别达8.1%、38.8%、55.2%和64.2%。水稻收获后土壤固碳量随生物炭添加量的提高呈增加趋势，单位质量（kg）生物炭的土壤固碳量并非随生物炭添加量提高而持续增加，添加量为15.0 t hm⁻²时达到最高值0.361 kg。与不添加生物炭处理相比，添加22.5 t hm⁻²水稻秸秆生物炭显著增加水稻产量，增幅达14.5%；显著降低N₂O和CH₄累积排放量分别达19.9%和51.6%，显著降低稻田综合增温潜势、净增温潜势和温室气体排放强度分别达49.9%、291.7%和55.3%。
结论综合作物增产、土壤固碳和温室气体减排效应，添加22.5 t hm⁻²水稻秸秆生物炭可以作为稻田固碳减排的最优策略。

Abstract:
Objective The effects of different biochar additions on soil carbon sequestration and greenhouse gas emissions were studied in Southern rice fields in China, to provide a theoretical basis and technical support for carbon sequestration and emission reduction in rice ecosystems.
Method Southern paddy soils were selected as research objects, 4 application rates of rice straw biochar were set under the conventional fertilization condition, which were 0, 7.5, 15.0 and 22.5 t hm⁻², respectively, with no fertilization and no biochar addition as the control. The soil physical and chemical properties, soil carbon sequestration, greenhouse gas emission, and rice yield were measured, and the net warming potential and greenhouse gas emission intensity were evaluated.
Result The addition of 22.5 t hm⁻² rice straw biochar significantly reduced soil bulk density by 5.1% compared with the treatment without biochar, and significantly increased soil pH, total nitrogen, available phosphorus and available potassium by 8.1%, 38.8%, 55.2% and 64.2%, respectively. Soil carbon sequestration after rice harvest increased with the increase of biochar addition. Soil carbon sequestration per kg of biochar did not increase continuously with the increase of biochar addition and reached the highest value of 0.361 kg when the biochar amount was 15.0 t hm⁻². Compared to the treatments without biochar, the treatment with 22.5 t hm⁻² rice straw biochar significantly increased the rice yield by 14.5%. Compared with no fertilization treatment, the N₂O, CH₄ and CO₂ emission fluxes were increased under all fertilization conditions. Compared with the treatment without the addition of biochar, the treatment with 22.5 t hm⁻² rice straw biochar significantly reduced the cumulative emission of N₂O and CH₄ by 19.9% and 51.6%, and significantly reduced global warming potential, net global warming potential, and greenhouse gas emission intensity by 49.9%, 291.7% and 55.3%, respectively.
Conclusion The addition of 22.5 t hm⁻² rice straw biochar can be chosen as the optimal strategy for carbon sequestration and emission reduction in a rice paddy, which will help to achieve China's dual-carbon goal.

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