Abstract

Small changes in the large stock of soil organic carbon (SOC) can have a substantial influence on the climate impact of agriculture. We used information from a Swedish soil monitoring program, in combination with farm census data, to analyze decadal SOC concentrations and SOC stock changes on dairy farms compared with other farm types, and to quantify the climate impact of these changes on dairy farms. Soil monitoring data included topsoil samples from two inventories on 159 dairy farms, 86 beef farms, 318 arable farms, and 13 pig farms, taken at the same locations in 2001–2007 and 2011–2017. Concentrations of SOC on dairy farms (3.0%) were significantly higher than on arable farms (2.3%) and pig farms (2.4%), but not significantly different from beef farms (3.1%). SOC concentration was correlated with proportion of ley at farm scale. SOC stocks in the upper 20 cm increased significantly on dairy, beef, and arable farms, by 0.38, 0.14, and 0.21 Mg C ha⁻¹year⁻¹, respectively, between 2001–2007 and 2011–2017. For dairy farms, this corresponded to −1.4 Mg CO₂ ha⁻¹ and approximately −0.22 kg CO₂ kg⁻¹ energy-corrected milk, demonstrating that SOC changes could have a substantial influence on the climate footprint of milk.

摘要

大量土壤有机碳 (SOC) 的微小变化会对农业的气候影响产生重大影响。我们使用来自瑞典土壤监测计划的信息，结合农场普查数据，分析奶牛场与其他农场类型相比的十年 SOC 浓度和 SOC 库变化，并量化这些变化对奶牛场的气候影响。土壤监测数据包括 2001-2007 年和 2011-2017 年在同一地点采集的 159 个奶牛场、86 个牛肉场、318 个耕地和 13 个养猪场的两个清单的表土样本。奶牛场（3.0%）的 SOC 浓度显着高于耕地（2.3%）和养猪场（2.4%），但与牛肉场（3.1%）没有显着差异。SOC 浓度与农场规模的 ley 比例相关。^-1年^-1分别在 2001-2007 年和 2011-2017 年之间。对于奶牛场，这相当于 -1.4 Mg CO ₂ ha ^-1和大约 -0.22 kg CO ₂ kg ^-1能量校正牛奶，表明 SOC 变化可能对牛奶的气候足迹产生重大影响。