再生稻和双季稻田CH4排放对比研究

【目的】 为了探索生态可持续的稻作模式,对比研究了长江中下游地区双季稻和再生稻稻作模式的产量潜力和CH₄排放特征,以此为选取绿色、生态经济可持续的稻作模式提供科学依据。【方法】 于2017—2018年依托湖南省益阳市大通湖区宏硕生态农业农机合作社科研基地,设置了双季稻和再生稻2种模式,对比分析了产量潜力、稻田生育期间CH₄排放动态和稻田生态系统CH₄季节性累积排放规律以及评估了单位产量稻田CH₄排放。【结果】 试验期间,从产量方面来看,双季稻早稻产量为7.37 t·hm ^-2,再生稻头季产量为8.84 t·hm ^-2,头季相比早稻增产19.95%。双季稻晚稻产量为6.82 t·hm ^-2,再生稻再生季产量为3.39 t·hm ^-2,再生季相比晚稻减产50.29%。综合两季,双季稻总产量为14.19 t·hm ^-2,再生稻总产量为12.22 t·hm ^-2;从生育期间CH₄排放动态来看,双季稻在分蘖期和齐穗期左右排放较强峰值,再生稻除了在分蘖期和齐穗期有较强的排放以外,其在施用促芽肥时也出现了小峰值。但总体双季稻的排放范围（- 0.06—1.30 μmol·m ^-2·s ^-1）要高于再生稻的排放范围（- 0.01—0.70 μmol·m ^-2·s ^-1）;从稻田CH₄季节性累积排放来看,双季稻CH₄累积排放要高于再生稻。再生稻头季累积排放范围在23.90—266.59kg·hm ^-2,再生季累积排放范围在0.00—46.14 kg·hm ^-2。双季稻早稻季节累积排放范围在为35.57—251.29kg·hm ^-2,晚稻季节累积排放范围在为10.74—321.59 kg·hm ^-2。双季稻CH₄季节累积排放A-B（两叶一心至分蘖后期）段>B-C（分蘖后期至齐穗期）段>C-D（齐穗期至成熟期）段,且全生育期双季稻累积排放达922.35 kg·hm ^-2。再生稻CH₄累积排放B-C段>A-B段>C-D段,且全生育期CH₄累积排放为609.74 kg·hm ^-2,即相比对照双季稻,再生稻CH₄累积排放降低了33.89%;最后通过评估单位产量CH₄排放可知,早稻单位产量CH₄排放为0.069 kg·kg ^-1,头季单位产量CH₄排放为0.062 kg·kg ^-1,头季相比早稻减少了10.14%;晚稻单位产量CH₄排放为0.061 kg·kg ^-1,再生季单位产量CH₄排放为0.018 kg·kg ^-1,再生季相比晚稻降低了70.49%。综合两季,双季稻单位产量CH₄排放为0.065 kg·kg ^-1,再生稻单位产量CH₄排放为0.050 kg·kg ^-1,再生稻相比双季稻降低了23.08%。 【结论】 从单位产量下CH₄排放角度来看,在长江中下游双季稻的主产区扩大种植再生稻是为良策。

Comparative Study on CH4Emission from Ratoon Rice and Double-Cropping Rice Fields

【Objective】In order to explore the ecologically sustainable rice planting model, the yield potential and CH₄ emission characteristics of traditional double-cropping rice and emerging ratoon rice in the middle and lower reaches of the Yangtze River were compared, so as to provide a scientific basis for selecting a green and ecologically sustainable rice farming model.【Method】In 2017-2018, relying on the research base of Hongshuo Eco-Agricultural Machinery Company in Datonghu District, Yiyang City, Hunan Province, two models of double-cropping rice and ratoon rice were set up, and the yield potential, CH₄ emission dynamics and CH₄ seasonal cumulative emission were compared and analyzed to evaluate unit yield CH₄ emissions from paddy fields.【Result】During the experiment, from the aspect of yield, the yield of early rice was 7.37 t·hm ^-2, and the yield of main crop was 8.84 t·hm ^-2. Main crop yield increased by 19.95% compared with early rice; the late rice yield was 6.82 t·hm ^-2, and the ratoon crop was 3.39 t·hm ^-2. Compared with the late rice, the ratoon crop yield was reduced by 50.29%. In the two crops, the total yield of double-cropping rice was 14.19 t·hm ^-2, and the total yield of ratoon rice was 12.22 t·hm ^-2; in terms of CH₄ emission dynamics, double-cropping rice was highly polluted in the tillering and full-heading. In addition to strong emissions in the tillering and full-heading, the ratoon rice also appeared small peak when applying budding fertilizer. However, the emission range of the overall double-cropping rice (-0.06 to 1.30 μmol·m ^-2·s ^-1) was higher than that of the ratoon rice (- 0.01 to 0.70 μmol·m ^-2·s ^-1); from the seasonal cumulative emission of CH₄ in paddy fields, the cumulative emission of CH₄ in double-cropping rice was higher than that in ratoon rice. The cumulative emission range of main crop was from 23.90 to 266.59 kg·hm ^-2, and the ratoon crop was from 0 to 4.61 kg·hm ^-2. The cumulative emission range of early rice was from 35.57 to 251.29 kg·hm ^-2, and the late rice was from10.74 to 321.59 kg·hm ^-2. CH₄ seasonal cumulative emissions of double-cropping rice showed: A-B stage (two leaves-one heart to late-tillering) > B-C stage (late-tillering to full-heading) > C-D stage (full-heading to mature), and cumulative emissions of double-cropping rice during the whole growth period was up to 922.35 kg·hm ^-2. The cumulative emission of methane from ratoon rice was B-C stage>A-B stage>C-D stage, and the cumulative emission of methane during the whole growth period was 609.74 kg·hm ^-2. Compared with the double-cropping rice control, ratoon rice methane cumulative emissions decreased by 33.89%. Finally, by evaluating the unit yield methane emissions, the methane emission per unit yield of early rice was0.069 kg·kg ^-1, and the methane emission per unit yield of main crop was 0.062 kg·kg ^-1, which was 10.14% lower than that of early rice. The methane emission per unit yield of late rice was 0.061 kg·kg ^-1, the methane emission per unit of ratoon crop was0.018 kg·kg ^-1, and the ratoon crop was reduced by 70.49%, compared with the late rice. In the two crops, the methane emission per unit yield of double-cropping rice was 0.065 kg·kg ^-1, and the methane emission per unit yield of ratoon rice was 0.050 kg·kg ^-1, which was 23.08% lower than that of double-cropping rice.【Conclusion】Therefore, in terms of methane emissions per unit yield, expanding the cultivation of ratoon rice was a good strategy in the main producing areas of the double-cropping rice in the middle and lower reaches of the Yangtze River.