提高东北春玉米产量和资源利用效率降低碳足迹的优化综合管理措施

Integrated management improves spring maize yield and resources use efficiency, and reduces the carbon footprint in Northeast China

  • 摘要: 东北是我国最大的玉米产区, 但生产中长期以高产为目标的管理方式, 导致其生产系统成为巨大的温室气体排放源, 在保证产量的基础上采取有效措施提高资源利用效率并降低环境代价已成为产业发展的迫切需求。本研究选择东北平原中部半湿润区和半干旱区, 采用宽窄行(宽行90 cm, 窄行40 cm)和高密度(90 000株∙hm−2)种植, 在玉米15叶期喷施化控剂, 氮肥减施(半湿润区和半干旱区分别减少28.0%和9.1%)的综合管理模式(IM), 其中半干旱区增加了膜下滴灌处理。从玉米产量、温光利用效率、经济效益和碳足迹等方面, 比较分析了东北不同生态类型区IM和农户模式(FM: 65 cm等行距, 种植密度60 000株·hm−2, 不化控)的差异。结果表明, 与FM相比, 半湿润区和半干旱区IM玉米产量分别提高24.2%和25.6%, 主要表现为种植密度增加50%使得收获穗数增加52.8%, 而穗粒数和千粒重仅分别降低8.5%和11.0%; 半湿润区积温生产效率提高21.1%, 光能利用效率提高21.0%, 半干旱区积温生产效率和光能利用效率分别提高20.7%和22.0%; 而且半湿润区和半干旱区IM年净收益分别较FM增加32.9%和24.4%。同时, 半湿润区IM碳排放总量为2860.1 kg(CO2-eq)·hm−2, 较FM降低18.7%; 而半干旱区IM的碳排放总量为 2729.6 kg(CO2-eq)·hm−2, 较FM增加8.9%。半湿润区和半干旱区IM单位玉米产量的碳足迹分别为0.20 kg(CO2-eq)·kg−1和0.22 kg(CO2-eq)·kg−1, 分别较FM降低39.4%和15.4%。综上, 在东北春玉米区采取综合管理措施, 能够实现玉米产量、温光资源利用效率和经济效益协同提升, 且显著降低其碳足迹, 其中半湿润区效果尤为明显, 而半干旱区碳排放虽有所增加, 但其增幅低于产量增幅, 最终显著降低碳足迹。所以, 该综合管理模式可在东北玉米生产中推荐应用。

     

    Abstract: Northeast China is the largest maize production region in the country, but the long-term management approach of production aiming at high yield has led to the cropping system becoming a major source of greenhouse gas emissions. Effective measures to improve resource efficiency and reduce environmental costs based on guaranteed yields have become an urgent need for industrial agricultural development. In this study, an integrated management mode (IM), including wide- and narrow-row alternative planting (90 cm for wide rows and 40 cm for narrow rows), high planting density (90 000 plants∙hm−2), application of chemical regulation agents at the 15-leaf spread of maize, and reduction of nitrogen fertilizer (28.0% and 9.1% in semi-humid and semi-arid areas, respectively) was selected in the semi-arid and semi-humid areas of the central Northeast Plain, while sub-membrane drip irrigation was applied in the semi-arid area, in 2019 and 2020. The differences between IM and farmers’ mode (FM: 65 cm equal row spacing and planting density 60 000 plants∙hm−2 without chemical regulation) in different ecological areas in Northeast China were comparatively analyzed in terms of maize grain yield, and use efficiencies of accumulated temperature and light energy, economic benefits, and carbon footprints. The results showed that, compared with FM, maize yield of IM in the semi-humid and semi-arid areas averagely increased by 24.2% and 25.6%, respectively, mainly because of a 50% increase in planting density resulting in 48.5% and 57.0% increases in the number of harvested ears; whereas the number of ears and thousand-kernel weight only decreased by 8.5% and 11.0% averagely in two areas for two years, respectively. The cumulated temperature production efficiency in the semi-humid area increased by 21.1%, the light energy use efficiency increased by 21.0%; in the semi-arid area, the cumulated temperature production efficiency and light energy use efficiency improved by 20.7% and 22.0%, respectively. Therefore, the annual net returns of IM in the semi-humid and semi-arid areas increased averagely by 32.9% and 24.4%, respectively, compared with FM. Meanwhile, the total carbon emission of IM in the semi-humid area was 2860.1 kg (CO2-eq)·hm−2, which was 18.7% lower than that of FM; while the total carbon emission of IM in the semi-arid area was 8.9% higher than that of FM, at 2729.6 kg (CO2-eq)·hm−2. The carbon footprint per unit grain yield of IM in the semi-humid and semi-arid areas was 0.20 kg (CO2-eq)·kg−1 and 0.22 kg(CO2-eq)·kg−1, respectively, which was 39.4% and 15.4% lower than that of FM. In summary, the IM in Northeast China was able to achieve synergistic improvements in grain yield, accumulated temperature production efficiency, light energy utilization efficiency, and economic benefits, and significantly reduce the carbon footprint, especially in the semi-humid area; the semi-arid area showed increased carbon emissions but had a higher yield increase than the semi-humid area, which ultimately also significantly reduced the carbon footprint. Therefore, an integrated management mode is recommended for maize production in Northeast China.

     

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