Abstract Use of eddy covariance (EC) as part of net ecosystem carbon balance (NECB) studies of grazed grasslands has the potential to provide valuable insights into the influence of management on soil carbon (C) stocks and opportunities for potential mitigation. However, in rotationally grazed systems where the EC measurements extend across multiple paddocks, often due to necessity, interpretation of results can be complicated by differing paddock-scale management regimes despite being the same land use with a single overarching farm-scale management approach. Here, we calculated separate annual CO2 fluxes and NECBs for two adjacent paddocks under the same general land management using a single EC system for seven years. We were interested in determining whether fluxes and annual NECB of the paddocks were sufficiently similar to allow future side-by-side comparisons of management practices aimed at increasing soil C. We assigned the half-hourly flux measurements to individual paddocks (P31 and P32) using footprint analysis and then gap filled each dataset separately. Additionally, we calculated annual fluxes (and NECBs) for the integrated area of both paddocks (i.e. using all measured flux data; referred to as NewMix). The mean (± 95% confidence interval) NECB for P31 and P32 were 1 ± 76 g C m−2 y−1, and 7 ± 80 g C m−2 y−1, which compared well with the NECB of NewMix (–14 ± 48 g C m−2 y−1). Large between-paddock and inter-annual variability were observed, and several consecutive years of data were required to determine with high certainty that both paddocks were C neutral. Day-to-day management decisions were identified as causing some of the variability. We concluded that the calculation of fluxes and NECB's from two adjacent paddocks using a single EC system was possible, and indeed, likely more insightful and useful than integrating across multiple paddocks. Such an approach can provide opportunities to more accurately quantify management effects, and test mitigation strategies by using treatment and control experiments on adjacent paddocks using a single EC system, although multiple measurement years are likely required. Alternatively, using two EC systems at separate sites, each quantifying both treatment and control fluxes would allow for replication, and thus greater statistical power, which has been a limitation for many EC based NECB studies.

中文翻译：

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从一个涡流协方差系统分别确定的两个相邻围场的温带放牧草地碳平衡

摘要 使用涡流协方差 (EC) 作为放牧草地净生态系统碳平衡 (NECB) 研究的一部分，有可能为管理对土壤碳 (C) 储量的影响和潜在缓解机会的影响提供有价值的见解。然而，在 EC 测量扩展到多个围场的轮牧系统中，通常由于必要性，尽管使用单一总体农场规模管理方法的土地使用相同，但由于不同的围场规模管理制度，结果的解释可能会变得复杂。在这里，我们使用单个 EC 系统计算了在相同的一般土地管理下两个相邻围场的单独​​年度 CO2 通量和 NECBs 七年。我们感兴趣的是确定围场的通量和年度 NECB 是否足够相似，以允许未来对旨在增加土壤 C 的管理实践进行并排比较。我们将半小时通量测量分配给各个围场（P31 和 P32）使用足迹分析，然后分别填充每个数据集。此外，我们计算了两个围场综合面积的年通量（和 NECBs）（即使用所有测得的通量数据；称为 NewMix）。P31 和 P32 的平均值（± 95% 置信区间）NECB 为 1 ± 76 g C m−2 y−1 和 7 ± 80 g C m−2 y−1，与 NewMix 的 NECB 相比（– 14 ± 48 g C m−2 y−1)。观察到大的围场间和年际变化，并且需要连续几年的数据来高度肯定地确定两个围场都是 C 中性的。日常管理决策被确定为导致一些可变性。我们得出的结论是，使用单个 EC 系统计算来自两个相邻围场的通量和 NECB 是可能的，并且实际上，可能比跨多个围场进行集成更深入和有用。这种方法可以提供机会更准确地量化管理效果，并通过使用单个 EC 系统对相邻围场进行处理和控制实验来测试缓解策略，尽管可能需要多个测量年。或者，在不同的地点使用两个 EC 系统，每个系统都量化处理和控制通量将允许复制，从而获得更大的统计功效，