Changes in soil organic carbon (SOC) storage in agricultural land are an important part of the Land Use, Land-Use Change and Forestry component of national greenhouse gas emission inventories. Furthermore, as climate mitigation strategies and incentives for carbon farming are being developed, accurate estimates of SOC stocks are essential to verify any management-induced changes in SOC. Based on agricultural mineral soils in the Danish soil-monitoring network, we analysed management effects on SOC stocks using data from the two most recent surveys (2009 and 2019). Between 2009 and 2019, the average increase in SOC stock was 1.2 Mg C ha⁻¹ for 0–50 cm despite a loss of 1.2 Mg C ha⁻¹ from the topsoil (0–25 cm), stressing the importance of including deeper soil layers in soil-monitoring networks. Comparing all four national surveys (1986, 1997, 2009, 2019), the mean SOC stock of mineral soils in Denmark appears stable. The change in SOC stock between 2009 and 2019 was analysed in detail in relation to management practices as reported by farmers. We found that the effects of single management factors were difficult to isolate from co-varying factors including soil parameters and that the use of farm management data to explain changes in SOC stocks observed in soil-monitoring networks appears limited. Uncertainty in SOC stock estimates also arises from low sampling frequency and statistical challenges related to regression to the mean. However, repeated stock measurements at decadal intervals still represent a benchmark for the overall development in regional and national SOC storage, as affected by actual farm management.

中文翻译：

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农场管理数据在分析丹麦土壤监测网络中 SOC 储量的年代际变化时的局限性

农业用地土壤有机碳 (SOC) 储存的变化是国家温室气体排放清单的土地利用、土地利用变化和林业组成部分的重要组成部分。此外，随着气候缓解战略和碳农业激励措施的制定，准确估计 SOC 库存对于验证任何管理引起的 SOC 变化至关重要。基于丹麦土壤监测网络中的农业矿质土壤，我们使用最近两次调查（2009 年和 2019 年）的数据分析了管理对 SOC 库存的影响。2009 年至 2019 年期间，尽管损失了1.2 Mg C ha ^-1 ，但 0-50 cm的 SOC 储量平均增加了1.2 Mg C ha ^-1从表土（0-25 厘米），强调在土壤监测网络中包括更深的土壤层的重要性。比较所有四项国家调查（1986 年、1997 年、2009 年、2019 年），丹麦矿质土壤的平均 SOC 存量似乎很稳定。根据农民报告的管理实践，详细分析了 2009 年至 2019 年 SOC 库存的变化。我们发现单一管理因素的影响很难从包括土壤参数在内的共同变化因素中分离出来，并且使用农场管理数据来解释在土壤监测网络中观察到的 SOC 储量的变化似乎是有限的。SOC 存量估计的不确定性还源于低采样频率和与均值回归相关的统计挑战。然而，