Carbon fluxes and budgets of intensive crop rotations in two regional climates of southwest Germany
Carbon fluxes and budgets of intensive crop rotations in two regional climates of southwest Germany
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DOI：
10.1016/j.agee.2019.02.011
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发表时间：
2019-04
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通讯作者：
A. Poyda;H. Wizemann;J. Ingwersen;Ravshan Eshonkulov;P. Högy;M. S. Demyan;Pascal Kremer;V. Wulfmeyer;T. Streck
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作者：
A. Poyda;H. Wizemann;J. Ingwersen;Ravshan Eshonkulov;P. Högy;M. S. Demyan;Pascal Kremer;V. Wulfmeyer;T. Streck
农田的碳封存潜力最近成为争论的话题，因为它可能对缓解全球气候变化做出重大贡献。相比之下，由于土壤有机碳（SOC）损失，过去几十年来德国农田的二氧化碳（CO2）排放量持续增加。然而，根据长期实验和最近的涡度协方差（EC）测量，欧洲农田的碳汇或源函数得到了对比结果。在八年的时间里（2010-2017），我们使用 EC 技术测量了德国西南部两个气候不同地区（Kraichgau (KR) 和 Swabian Jura (SJ)）六个集约化管理农田的 CO2 净生态系统交换 (NEE)。此外，我们测量了三个发育阶段的地上作物生物量，并估计了与管理相关的碳输入和输出。年度累计NEE的年际现场变异性较大，区域和不同站点对NEE预算均没有显着影响。冬油菜在观测作物中的CO2吸收能力最低，冬油菜收获年份的年平均NEE显着低于冬小麦、青贮玉米和冬大麦。平均超过 46 个站点年，年 NEE 显示明显的 CO2 吸收量为 −2580kg CO2-C ha−1yr−1。考虑到与管理相关的碳通量，所得的净生物群落生产力（NBP）表明研究地点的碳源功能，年平均损失为 1190kgCha−1yr−1。由于整株收获后碳去除量较高，青贮玉米种植导致碳损失显着高于冬油菜、冬小麦和冬大麦，达 4280kgCha−1yr−1，年平均 NBP 分别为 1430、−188 和−1340kgCha−1yr−1。因此，出口碳在年度 NBP 中所占的比例越高，导致碳损失越高。我们的结论是，最近青贮玉米在轮作中重要性的增加破坏了土壤有机碳储量的稳定性，威胁到加强土壤碳固存的努力。这需要对更多样化的作物轮作（包括多年生阶段）的碳固存潜力进行进一步研究。
The carbon (C) sequestration potential of croplands has recently become a subject of debate because it may contribute significantly to global climate change mitigation. By contrast, carbon dioxide (CO2) emissions from German croplands have continuously increased over the past decades as a result of soil organic carbon (SOC) losses. Contrasting results, however, have been obtained on the C sink or source function of European croplands based on long-term experiments and rather recent eddy covariance (EC) measurements. Over a period of eight years (2010–2017), we measured the net ecosystem exchange (NEE) of CO2on six intensively managed cropland sites in two climatically different regions of southwest Germany (Kraichgau (KR) and Swabian Jura (SJ)) using the EC technique. Additionally, we measured aboveground crop biomass at three development stages and estimated management-related C inputs and exports. The inter-annual on-site variability of cumulated annual NEE was large, and neither the region nor the different sites significantly affected NEE budgets. Winter rapeseed showed the lowest CO2uptake capacity among the observed crops, and the mean annual NEE in the years with winter rapeseed harvest was significantly lower compared to winter wheat, silage maize and winter barley. On average over 46 site-years, annual NEE showed a distinct CO2uptake of −2580 kg CO2-C ha−1yr−1. Considering management-related C fluxes, the resulting net biome productivity (NBP) indicated a C source function of the study sites with mean annual losses of 1190 kg C ha−1yr−1. Due to high C removals after whole plant harvests, silage maize cropping resulted in significantly higher C losses of 4280 kg C ha−1yr−1compared to winter rapeseed, winter wheat and winter barley, with mean annual NBPs of 1430, −188 and −1340 kg C ha−1yr−1, respectively. Consequently, a higher share of exported C in annual NBP resulted in higher C losses. We conclude that the recently increased importance of silage maize in crop rotations destabilizes SOC stocks, threatening the efforts in enhancing soil C sequestration. This calls for further investigations on the C sequestration potentials of more diverse crop rotations including perennial phases.