Decarbonization of the world's energy supply is essential to meet the targets of the 2016 Paris climate change agreement. One promising opportunity is the utilization of second generation, low input bioenergy crops such as Miscanthus and Short Rotation Coppice (SRC) willow. Research has previously been carried out on the greenhouse gas (GHG) balance of growing these feedstocks and land‐use changes involved in converting conventional cropland to their production; however, there is almost no body of work understanding the costs associated with their end of life transitions back to conventional crops. It is likely that it is during crop interventions and land‐use transitions that significant GHG fluxes might occur. Therefore, in this study, we investigated soil GHG fluxes over 82 weeks during transition from Miscanthus and SRC willow into perennial ryegrass in west Wales, UK. This study captured soil GHG fluxes at a weekly time step, alongside monthly changes in soil nitrogen and labile carbon and reports the results of regression modelling of suspected drivers. Methane fluxes were typically trivial; however, nitrous oxide (N₂O) fluxes were notably affected, reverted plots produced significantly more N₂O than retained controls and Miscanthus produced significantly higher fluxes overall than willow plots. N₂O costs of reversion appeared to be contained within the first year of reversion when the Miscanthus plots produced an average pregrass flux of 0.13 mg N₂O m⁻² hr⁻¹ while for willow, this was 0.03 mg N₂O m⁻² hr⁻¹. Total N₂O emission from reversion increased the carbon cost over the lifetime of the Miscanthus from 6.50 to 9.91 Mg CO₂ eq. ha⁻¹ while for the willow, this increase was from 9.61 to 10.42 Mg CO₂ eq. ha⁻¹. Despite these significant increases, the carbon cost of energy contained in these perennial crops remained far lower than the equivalent carbon cost of energy in coal.

中文翻译：

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土地利用从芒草和 SRC 柳树恢复为多年生黑麦草后的土壤一氧化二氮通量。

世界能源供应脱碳对于实现 2016 年巴黎气候变化协议的目标至关重要。一个有希望的机会是利用第二代低投入生物能源作物，如芒草和短轮生林 (SRC) 柳树。此前已经对种植这些原料的温室气体（GHG）平衡以及将传统农田转为生产所涉及的土地利用变化进行了研究；然而，几乎没有任何工作了解其生命周期结束时转回传统作物的相关成本。在作物干预和土地利用转变期间，可能会出现显着的温室气体通量。因此，在这项研究中，我们调查了英国威尔士西部从芒草和 SRC 柳转变为多年生黑麦草期间 82 周内的土壤温室气体通量。这项研究捕获了每周时间步长的土壤温室气体通量，以及每月土壤氮和活性碳的变化，并报告了可疑驱动因素的回归模型结果。甲烷通量通常微不足道；然而，一氧化二氮 (N _{2 O) 通量受到显着影响，恢复样地产生的 N 2} O明显多于保留对照，而芒草总体产生的通量显着高于柳样样地。回归的N ₂ O 成本似乎包含在回归的第一年内，当时芒草地块产生的平均草前通量为 0.13 mg N ₂ O m ⁻²  hr ⁻¹，而对于柳树，这是 0.03 mg N ₂ O m ^{− 2} 小时^-1。回归引起的总 N ₂ O 排放使芒草生命周期中的碳成本从 6.50 Mg CO 2 当量增加到 9.91 Mg CO ₂ 当量。ha ^-1而对于柳树，该增加量从 9.61 Mg CO ₂当量增加到 10.42 Mg CO 2 当量。哈⁻¹。尽管这些显着增加，这些多年生作物所含能源的碳成本仍然远低于煤炭能源的同等碳成本。