Impact of water table levels and winter cover crops on greenhouse gas emissions from cultivated peat soils.
Impact of water table levels and winter cover crops on greenhouse gas emissions from cultivated peat soils.
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DOI：
10.1016/j.scitotenv.2019.135130
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发表时间：
2019-11
期刊：
影响因子：
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通讯作者：
Yuan Wen;H. Zang;Qingxu Ma;B. Freeman;D. Chadwick;C. Evans;Davey L. Jones
中科院分区：
文献类型：
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作者：
Yuan Wen;H. Zang;Qingxu Ma;B. Freeman;D. Chadwick;C. Evans;Davey L. Jones
排水和耕作已经把泥炭地从碳汇变成了温室气体排放的热点。提高地下水位和种植冬季覆盖作物是帮助减少泥炭氧化和重新启动非种植期净碳积累的潜在策略。然而，这些做法及其相互作用对温室气体排放的影响尚不清楚。为了研究地下水位（- 30 cm和- 50 cm）和冬季覆盖作物（紫薇、黑麦和不种植）对冬季（11月- 4月）二氧化碳（CO2）、氧化亚氮（N2O）和甲烷（CH4）通量的影响，我们进行了室外中尺度试验。监测了土壤-大气温室气体交换、泥炭剖面内温室气体浓度和土壤水溶质浓度。研究结果表明，高地下水位显著降低了生态系统呼吸，但对N2O和ch4通量没有净影响。覆盖作物对速效氮的吸收显著降低了土壤溶液中的硝酸盐，从而降低了淋溶的可能性以及直接和间接的N2O排放。在任何测量的温室气体通量中，未发现地下水位与覆盖作物之间存在相互作用。温室气体通量的季节变化与- 15 cm和- 40 cm深度的土壤空气浓度呈正相关，并进一步受到土壤中溶解有机碳、硝酸盐浓度和厌氧条件的调节。这项研究表明，通过提高地下水位和种植绿色覆盖作物来减少温室气体排放具有很大的潜力。需要进一步的研究来完成对这些策略在生长季节之外的完整评估，这可能在富含碳的泥炭地提供显著的缓解效益。
Drainage and cultivation have turned peatlands from carbon (C) sinks into hotspots for greenhouse gas (GHG) emissions. Raising the water table and planting of winter cover crops are potential strategies to help reduce peat oxidation and re-initiate net C accumulation during the non-cropping period. However, the effects of these practices as well as their interactions on GHG emissions remain unclear. Here, we carried out an outdoor mesocosm experiment to elucidate the effect of water table levels (−30 cm and −50 cm) and winter cover crop cultivation (vetch, rye, no plant) on carbon dioxide (CO2), nitrous oxide (N2O) and methane (CH4) fluxes during the winter period (November-April). Soil-atmosphere GHG exchange, GHG concentrations within the peat profile and soil water solute concentrations were monitored. Our results showed that high water table significantly reduced ecosystem respiration, while it had no net effect on N2O and CH4fluxes. Uptake of available N by the cover crop significantly reduced nitrate in soil solution, thereby lowering the potential for leaching and both direct and indirect N2O emissions. No interactive effects between water table levels and cover crops were detected for any of the measured GHG fluxes. Seasonal variations of GHG fluxes were positively correlated with soil air concentrations at −15 cm and −40 cm depths, which were further regulated by dissolved organic C, nitrate concentration, and anaerobic conditions in the soil. This study suggests that there is great potential to raise water table levels and introduce green cover crops to reduce GHG emissions. Further studies are needed to achieve a complete evaluation of these strategies outside of the growing season, which may provide a significant mitigation benefit in C-rich cultivated peatlands.