秸秆还田、一膜两年用及间作对农田碳排放的短期效应

Short-term response of farmland carbon emission to straw return, two-year plastic film mulching and intercropping

  • 摘要: 针对作物高产模式碳排放高、生产实践中缺乏减排理论和技术问题, 通过田间试验, 探讨了不同秸秆还田方式、地膜一膜两年用及间作对小麦、玉米农田碳排放特征的影响, 以期为碳减排种植模式及配套技术的构建提供理论与实践依据。结果表明, 间作具有显著的碳减排作用, 与传统单作小麦、玉米相比, 小麦||玉米间作全生育期平均碳排放总量减少279~876 kg·hm2, 减幅达5.1%~16.0%,达到显著性差异。免耕秸秆还田及免耕一膜两年用可降低次年农田土壤的碳排放, 免耕秸秆还田单作小麦较传统翻耕处理CO2排放显著减少648~966 kg·hm2, 减幅21.3%~31.8%; 免耕一膜两年用单作玉米较翻耕覆新膜传统处理碳减排632 kg·hm2, 减幅10.0%, 差异显著。小麦秸秆还田及地膜两年用集成应用于小麦间作玉米进一步提高了间作的碳减排效应, 与传统间作处理(CTI1)相比, 间作小麦高留茬免耕结合一膜两年用处理(NTSSI2)和小麦秸秆还田覆盖结合一膜两年用处理(NTSI2)的碳排放总量分别降低471 kg·hm2与518 kg·hm2, 降幅分别为9.2%与10.1%, 达到显著水平; NTSSI2和NTSI2的总固碳量/土壤呼吸释放总碳量(NPPC/Ras)值分别为13.7与14.0, 较CTI1分别高19.1%与21.7%, 即NTSI2减排、碳汇潜力更为突出。因此, 小麦高茬25~30 cm秸秆覆盖免耕结合一膜两年用间作 (NTSI2)可作为干旱绿洲灌区碳减排、碳增汇高效农作制模式。

     

    Abstract: In conventional crop production, high yield has always meant high carbon emissions. It has therefore become urgent to develop theoretical and practical strategies for high yield with low carbon emissions in modern agriculture. In this study, a field experiment was conducted in a typical oasis irrigation region to determine the integrated response of carbon emission in wheat-maize intercropping systems under different straw-return (straw standing, straw mulching and no-mulching), plastic film mulching (mulching for one year and two years), cropping (wheat-maize intercropping, monoculture of wheat and maize) and tillage (no-tillage, conventional tillage) patterns. The results showed that intercropping significantly decreased soil carbon emissions in farmlands. Compared with monoculture wheat and maize under conventional tillage management, the averaged total soil CO2 emissions in wheat-maize intercropping systems reduced by a range of 279–876 kg·hm-2, the equivalent of 5.1%–16.0%. No tillage with straw-return and plastic film mulching for 2-year reduced soil carbon emissions in the next year. No-tillage in combination with straw-return to soil decreased total soil CO2 emissions by 648–966 kg·hm-2, the equivalent of 21.3%31.8%, than conventional tillage without straw-return to soil in mono-cropped wheat field. Plastic film mulching for two years reduced total soil CO2 emissions by 632 kg·hm-2 compared with that of conventional tillage in mono-cropped maize. In particular, wheat-maize intercropping in combination with straw-return to soil and 2-year plastic film mulching further reduced the carbon emissions. Compared with conventional intercropping with plastic film mulching for 1-year and conventional tillage (CTI1), wheat-maize intercropping with 25–30 cm of standing straw, 2-year plastic film mulching and no-tillage (NTSSI2) and wheat-maize intercropping with 25–30 cm straw mulching on the soil and 2-year plastic film mulching and no-tillage (NTSI2) reduced total soil CO2 emissions by 471 kg·hm-2 and 518 kg·hm-2, the equivalent of 9.2% and 10.1%, respectively. The carbon sequestration potential (ratio of total plant carbon fixation to total soil carbon emission, i.e., NPPC/Ras) were 13.7 and 14.0, respectively, in NTSSI2 and NTSI2 treatments, they were higher by 19.1% and 21.5% than that of CTI1, respectively. This indicated that NTSI2 had a more prominent potential for reducing carbon emissions and enhancing carbon sequestration. Thus, NTSI2 was recommended as the best farming pattern due to its high-efficiency of carbon emission reduction and carbon sequestration in irrigated arid oasis regions.

     

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