典型单季稻蓄留再生稻的温室气体排放观测研究
Observation study on GHG emissions from ratoon rice field transformed from the typical single-cropping rice fields
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摘要: 为研究在典型单季稻区和种植水稻光热条件”一季有余, 两季不足”的地区推广蓄留再生稻的温室气体排放特征, 在太湖流域使用静态箱—气相色谱法对稻—麦(RW)、稻—油菜(RO)、稻—甘蓝(RC)、稻—紫云英(RA)、稻—冬闲(RF)和稻—再生稻—紫云英(Rr) 6个种植模式进行为期1周年的温室气体排放田间原位观测研究。结果表明, 单季稻处理(RW、RO、RC、RF、RA)和再生稻处理(Rr)的周年CH4排放量分别为43.8 ~ 135 kg (CH4)∙hm-2和541 kg (CH4)∙hm-2, 周年N2O排放量分别为8.16 ~ 19.7 kg (N) ∙hm-2和4.30 kg (N) ∙hm-2; 周年产量分别为6.99 ~ 11.0 t hm-2和14.1 t hm-2。与单季稻处理相比, 再生稻处理周年CH4排放量显著增加3.01~11.4倍, 周年N2O排放量显著减少47.3%~78.1%, 周年温室气体排放总量(TGHG)显著增加64.1% ~ 240%, 周年产量显著增加27.5% ~ 102%, 周年温室气体排放强度(GHGI)增加14.7% ~ 68.7%。Rr模式下头季秸秆还田使得再生季CH4排放显著增加, 进而导致Rr处理的TGHG显著高于5种单季稻种植模式。综上所述, 在典型单季稻区蓄留再生稻能显著增加农作物总产量, 但同时也提高了GHGI, 因此, 建议加强再生稻田间水分管理, 并将头季秸秆推迟至再生季收获后还田以减少CH4排放, 达到丰产和减排兼顾的目的。Abstract: To investigate the greenhouse gas emission characteristics of promoting ratoon rice retention in typical single-season rice areas and regions with insufficient thermal conditions for double cropping, a one-year in-situ field study on greenhouse gas emissions was conducted in the Taihu Basin using static chambers and gas chromatography. Six cropping systems were examined: rice-wheat (RW), rice-oilseed rape (RO), rice-cabbage (RC), rice-Astragalus. (RA), rice-fallow (RF), and rice-ratoon rice- Astragalus. (Rr). Results showed that the annual CH₄ emissions for single-season rice systems (RW, RO, RC, RF, RA) ranged from 43.8 to 135 kg (CH₄)∙hm⁻², while that of the ratoon rice system (Rr) was 541 kg (CH₄)∙hm⁻². Annual N₂O emissions ranged from 8.16 to 19.7 kg (N)∙hm⁻² for single-season rice systems and 4.30 kg (N)∙hm⁻² for the ratoon rice system. Annual yields were 6.99 to 11.0 t∙hm⁻² for single-season rice systems and 14.1 t∙hm⁻² for the ratoon rice system. Compared to single-season rice systems, the ratoon rice system showed significantly higher annual CH₄ emissions, increasing by 3.01 to 11.4 times, and significantly lower annual N₂O emissions, decreasing by 47.3% to 78.1%. Total greenhouse gas emissions (TGHG) increased significantly by 64.1% to 240%, and annual yields increased significantly by 27.5% to 102%. Greenhouse gas emission intensity (GHGI) increased by 14.7% to 68.7%. The straw return in the main season under the Rr system significantly increased CH₄ emissions during the ratoon season, leading to higher TGHG in the ratoon rice system compared to the five single-season rice systems. In conclusion, ratoon rice retention in typical single-season rice areas can significantly increase total crop yield but also raises GHGI. It is therefore recommended to strengthen water management in ratoon rice fields and delay straw return until after the ratoon harvest to reduce CH₄ emissions, achieving the dual goals of high yield and reduced emissions.