Elevation of NO3−-N from biochar amendment facilitates mitigating paddy CH4 emission stably over seven years. (15th February 2022)

• Record Type: Journal Article
• Authors: Nan, Qiong; Fang, Chenxuan; Cheng, Linqi; Hao, Wang; Wu, Weixiang
• Is Part Of: Environmental pollution. Volume 295(2022)
• Publication Date: 2022-02-15
• Subjects: Paddy field -- Methane -- Biochar -- Carbon neutral -- Long-term; Pollution -- Periodicals; Pollution -- Environmental aspects -- Periodicals; Environmental Pollution -- Periodicals; Pollution -- Périodiques; Pollution -- Aspect de l'environnement -- Périodiques; Pollution -- Effets physiologiques -- Périodiques; Pollution; Pollution -- Environmental aspects; Periodicals; Electronic journals; 363.73
• DOI: 10.1016/j.envpol.2021.118707
• Languages: English
• ISSNs: 0269-7491

Abstract

Abstract: Biochar application into paddy is an improved strategy for addressing methane (CH4 ) stimulation of straw biomass incorporation. Whereas, the differentiative patterns and mechanisms on CH4 emission of straw biomass and biochar after long years still need to be disentangled. Considering economic feasibility, a seven-year of field experiment was conducted to explore the long-term CH4 mitigation effect of annual low-rate biochar incorporation (RSC, 2.8 t ha −1 ), with annual rice straw incorporation (RS, 8 t ha −1 ) and control (CK, with no biochar or rice straw amendment incorporation) as a comparation. Results showed that RSC mitigated CH4 emission while RS stimulated CH4 significantly ( p < 0.05) and stably over 7 experimental years compared with CK. RSC mitigated 14.8–46.7% of CH4 emission compared with CK. In comparison to RSC, RS increased 111–950.5% of CH4 emission during 7 field experimental years. On the 7th field experimental year, pH was significantly increased both in RS and RSC treatment ( p < 0.05). RSC significantly ( p < 0.05) increased soil nitrate (NO3 − -N) compared with RS while RS significantly ( p < 0.05) increased dissolved carbon (DOC) compared to RSC. Soil NO3 − -N inhibition on methanogens and promotion on methanotrophs activities were verified by laboratory experiment, while soil pH and DOC mainly promoted methanogens abundance. Significantly ( p < 0.05) increased DOC and soil pH enhanced methanogens growth and stimulated CH4 emission in RS treatment. Higher soil NO3 − -N content in RSC than CK and RS contributed to CH4 mitigation. Soil NO3 − -N and DOC were identified as the key factors differentiating CH4 emission patterns of RS and RSC in 2019. Collectively, soil NO3 − -N impacts on CH4 flux provide new ideas for prolonged effect of biochar amendment on CH4 mitigation after years. Graphical abstract: Image 1 Highlights: Biochar mitigated while straw promoted CH4 emission for 7 years. NO3 − -N and DOC differentiated CH4 pattern of straw and biochar. NO3 − -N inhibited methanogens while promoted methanotrophs activities. NO3 − -N is significant in mitigating CH4 emission in paddy.