Engineered biochar effects on methane emissions and rice yield under alternate wetting and drying in paddy soils

초록

Biochar is a promising strategy for improving crop yield and mitigating greenhouse gas emissions. However, the impacts of acid modified biochar on CH4 emissions and yield in rice fields are not comprehensively understood, especially under alternate wetting and drying irrigation (IAWD). Here, we conducted a 3-yr (2019-2021) field experiment with two irrigation regimes (ICF: continuous flooding irrigation, IAWD) and three biochar treatments (B0: no biochar; B20: 20 t ha-1 rice straw biochar; and B20A: 20 t ha-1 acid modified rice straw biochar). Results showed IAWD reduced CH4 emissions by 63-80 % and water consumption by 10-12 % but threatened the rice soil fertility. B20 and B20A increased soil cation exchange capacity by 13-36 %, soil organic carbon by 24-44 % and C/N by 17-36 % over the three years. However, compared to B0, B20 tended to increase CH4 emissions and factor (CH4EF), reduced grain yield by 6 % in 2019, but B20A suppressed CH4 emissions by 19 % while maintaining a stable grain yield. B20 and B20A enhanced yield by 5 % and 8 %, 11 % and 12 % and decreased CH4 emissions by 22 % and 38 %, 38 % and 40 % in 2020 and 2021, respectively. B20A alleviated its initial negative impact on CH4 emissions and yield in 2019 due to acid modified biochar enhancing more acidic and oxygenated functional groups. IAWDB20A decreased CH4 emissions by 75-89 % and greenhouse gas emission intensity (GHGI) by 75-90 % compared to ICFB0 over the three years. Consequently, B20A coupled with IAWD achieves sustainable use of water resources, improves soil degradation and mitigates climate change.

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