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| Synergistic regulation mechanism of straw returning with lime to the field on greenhouse gas emissions in paddy field |
| Received:February 19, 2025 |
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| KeyWord:straw return;lime;soil acidification;greenhouse gas;soil microorganisms |
| Author Name | Affiliation | E-mail | | SUN Mengyu | School of Agronomy, Anhui Agricultural University, Hefei 230036, China | | | ZHAO Qiang | School of Agronomy, Anhui Agricultural University, Hefei 230036, China | | | WU Jing | School of Agronomy, Anhui Agricultural University, Hefei 230036, China | | | ZHANG Jun | School of Agronomy, Anhui Agricultural University, Hefei 230036, China | | | CHE Zhao | School of Agronomy, Anhui Agricultural University, Hefei 230036, China | | | WU Gong | School of Agronomy, Anhui Agricultural University, Hefei 230036, China | | | SONG He | School of Agronomy, Anhui Agricultural University, Hefei 230036, China | | | LI Xiaoxiao | School of Agronomy, Anhui Agricultural University, Hefei 230036, China | xxli@ahau.edu.cn |
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| Abstract: |
| To explore the mechanisms of greenhouse gas emissions under straw return combined with different lime application rates in acidic paddy soils. This study adopted a two-factor split-plot design. The main plots consisted of straw application treatments：no straw return（S0）and straw return（S1, 5 500 kg·hm-2）. The subplots included lime application treatments：no lime（L0）, low lime rate（L1, 3 500 kg·hm-2）, and high lime rate（L2, 7 000 kg·hm-2）. Measurements included greenhouse gas emissions（CH4 and N2O）, microbial abundance and community structure, soil nitrification potential, and denitrification capacity. The results are as follows：straw return increased CH4 emissions by 115.5% - 144.3%, and the mechanism of action was closely related to the increase of dissolved organic carbon（DOC）. Elevated DOC promoted the abundance of methanogens（Methanocella genus）while reducing the abundance of methane-oxidizing bacteria （pmoA gene）and key genera（Methyloparacoccus and Methylomicrobium）. Lime application decreased CH4 emissions by 21.9%-39.7%, driven by increased soil pH and NO3--N content, which enhanced pmoA gene abundance and suppressed methanogens（Methanobacterium genus）. Straw return reduced total N2O emissions by 33.0%-38.2%. The abatement mechanism is that the straw return effectively promotes the conversion of N2O to N2 reduction by decreasing the abundance of the narG gene and the relative abundance of the key denitrifying genera（Acidiphilium and Mycolicibacterium）and increasing the abundance of the nosZ gene. Lime application increased N2O emissions by 29.5%~65.0% through dual regulatory mechanisms. Specifically, reduced NH4+-N and DOC levels stimulated ammonia-oxidizing archaea （AOA）abundance, while elevated pH and NO3--N boosted narG gene abundance and suppressed nosZ gene activity, both of which together increased N2O production during nitrification and denitrification. Straw return increased global warming potential（GWP）and greenhouse gas emission intensity（GHGI）, while lime application was effective in reducing GWP and GHGI, where high lime application on straw fielding was able to reduce GHGI to 0.81 kg·kg-1, which was significantly lower than that of the L0S0 treatment. In conclusion, for strongly acidic paddy soils, combining straw return with high lime application（7 000 kg ·hm-2）effectively mitigates the problem of increased greenhouse gas emission caused by straw-returning. Thus, integrating lime with straw return represents a promising cultivation strategy to achieve greenhouse gas reduction and increase production in rice production systems. |
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