不同再生稻栽培模式氮足迹及经济效益评估

Assessment of nitrogen footprint and economic profit under different ratooning rice cultivation modes in central China

  • 摘要: 有关不同栽培措施下再生稻稻田温室气体排放、碳足迹与产量变化研究已取得较大进展, 然而不同再生稻栽培模式氮足迹尚不明确。因此, 本研究通过大田试验, 采用生命周期法, 研究了不同再生稻栽培模式 常规栽培模式(CM)和两个优化栽培模式(OM1和OM2)对水稻产量、氮足迹与经济效益的影响。其中, CM模式采用人工插秧、常规施肥、浅水淹灌、留茬高度20 cm与秸秆不还田等传统再生稻栽培技术, OM1模式采用机插秧、一次性缓释肥施用、干湿交替、头季留茬高度20 cm与秸秆还田, OM2模式采用机插秧、氮肥深施、干湿交替、头季留茬高度40 cm与秸秆还田配施腐熟剂。结果表明, OM2再生季产量和稻季总产量最高, 较CM和OM1分别提高再生季产量37.1% (P<0.05)和28.1% (P<0.05)、总产量21.7%和12.5% (P<0.05)。对于再生稻氮足迹构成, OM2具有最高间接活性氮排放。对于直接活性氮排放, 3个模式N2O排放无显著差异; 但对于头季稻NH3挥发, OM2比CM显著降低14.4% (P<0.05)。因此, OM2具有最低周年活性氮排放, 分别比CM和OM1显著降低10.9% (P<0.05) 和2.2% (P<0.05)。对于再生稻氮足迹, OM2比CM和OM1分别显著降低26.9% (P<0.05)和13.1% (P<0.05)。此外, OM2经济效益最高, 分别较OM1和CM提高20.9%和29.2%。本研究表明, OM2模式是一项降低氮足迹和提高经济效益的可持续再生稻栽培模式, 值得在我国南方再生稻区推广。

     

    Abstract: Significant progress has been made in studying greenhouse gas emissions, carbon footprints, and yield changes in ratooned rice fields across diverse cultivation practices. However, the nitrogen footprints of different ratooning rice cultivation methods remain unclear. Therefore, this field experiment used the life cycle assessment to study the effects of different ratooning rice cultivation modes conventional cultivation mode (CM) and two optimized cultivation modes (OM1 and OM2) on rice yield, nitrogen footprint, and economic outcomes. Among the three modes, the CM mode adopted traditional ratooning rice cultivation techniques, such as artificial transplanting, conventional fertilization, shallow flooding irrigation, stubble height of 20 cm, and excluding straw returning practices. The OM1 mode adopted mechanical transplanting, one-time application of slow-release fertilizer, dry-wet irrigation altenation, stubble height of 20 cm, and straw returning. The OM2 mode adopted mechanical transplanting, deep application of nitrogen fertilizer, dry-wet irrigation alternation, stubble height of 40 cm, and straw returning along with a decomposing agent. The results showed that OM2 had the highest yield in the ratooning season and the total yield in the rice season, which increased the yield in the ratooning season by 37.1% (P<0.05) and 28.1% (P<0.05) and the total yield by 21.7% and 12.5% (P<0.05), respectively, in comparison to CM and OM1. OM2 had the highest indirect active nitrogen emissions. In the context of direct active nitrogen emissions, there were no significant differences in the N2O emissions among the three modes. However, OM2 significantly reduced NH3 volatilization by 14.4% (P<0.05) in comparison to CM for main crop. Therefore, OM2 had the lowest annual active nitrogen emissions, which were significantly lower than CM and OM1 by 10.9% (P<0.05) and 2.2% (P<0.05), respectively. The nitrogen footprint of OM2 was significantly lower than that of CM and OM1 by 26.9% (P<0.05) and 13.1% (P<0.05), respectively. OM2 had the highest economic benefit, which was 20.9% and 29.2% higher than OM1 and CM, respectively. This study showed that the OM2 is a sustainable ratooning rice cultivation mode that effectively reduces nitrogen footprint while enhancing economic benefits. The potential for promoting this mode is substantial in the ratooning rice area of southern China.

     

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