Carbon farming has been recently proposed as an effective measure for climate change mitigation through carbon (C) sequestration or C emissions reduction. In order to identify and estimate the climate change mitigation potential of carbon farming practices on European croplands we conduct a systematic review on both relative and absolute annual soil organic carbon (SOC) stock change (ΔSOCREL; ΔSOCABS) related to single and combined agroecological practices tested on mineral soils at a minimum of 0–30 cm and up to 150 cm soil depth whenever data were available. We used the term ΔSOCREL for SOC stock changes determined by the paired comparison method and the term ΔSOCABS for those calculated using the SOC stock difference method. We compiled a dataset with more than 700 records on SOC change rates representing 12 carbon farming practices. Mean ΔSOCREL in Mg C ha−1 yr−1 at 0–30 cm soil depth were collected for cover crops (0.40 ± 0.32), organic amendments (0.52 ± 0.47 and 0.38 ± 0.37 when the control is respectively unfertilized or liquid organic amendment), crop residue maintenance (0.14 ± 0.06), improved rotations (0.21 ± 0.16), reduced soil disturbance (0.24 ± 0.34), silvoarable systems (0.21 ± 0.08), organic (0.9 Mg ± 0.25) and conservation management (0.78 ± 0.62), set-aside (0.75 ± 0.68 and −0.39 ± 0.50 when the control is respectively cropland or pasture/grassland), cropland conversion into permanent grassland (0.79 ± 0.47), poplar plantations (0.25 ± 0.68 and −0.85 ± 0.53 when established on cropland or pasture/grassland). SOC sequestration was detected only for organic amendments, cover crops, poplar plantations, conservation management, organic management, and combined carbon farming practices for which we estimated a median ΔSOCABS ranging between 0.32 and 0.96 Mg C ha−1 yr−1 at 0–30 cm. The ΔSOCABS observed at 0–30 cm soil depth from cropland conversion into short rotation forestry resulted in an increase of C, while negative values were observed when the control was grassland. Cropland conversion into permanent grassland or pasture showed positive ΔSOCREL at 0–30 and 0–90 and 0–100 cm soil depth. Reduced soil disturbance full soil profile assessment at 0–50 cm soil depth completely counterweighted any SOC stock increase found in topsoil at 0–30 and 0–40 cm soil depth, therefore resulting in no net climate benefit. Conservation management, organic management, and combining cover crops with organic amendments are the most effective strategies shifting arable land from C source to net sink, with median ΔSOCABS at 0–30 cm soil depth of 0.63, 0.91 and 0.96 Mg C ha−1 yr−1, respectively. Permanent grasslands and pastures were negatively affected by any type of land-use change, at least in topsoil. Natural ecological successions after cropland abandonment (20-year set-aside), or arable land conversion into poplar plantations and grassland promote relative SOC stock annual increase by 1.08, 0.77 and 0.33 at 0–30 cm respectively, while the net climate benefit remains unclear when subsoils are assessed.

中文翻译：

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欧洲农田的碳耕作方式：对土壤有机碳影响的综述


最近有人提出，碳农业是通过碳 （C） 封存或碳减排来缓解气候变化的有效措施。为了识别和估计欧洲农田碳耕作方式减缓气候变化的潜力，我们对相对和绝对年度土壤有机碳 （SOC） 存量变化（ΔSOCREL;ΔSOCABS）进行了系统评价，这些变化与单一和联合农业生态实践有关，只要有数据，就对矿物土壤进行了测试，土壤深度最小为 0-30 厘米，最长可达 150 厘米。我们使用术语 ΔSOCREL 表示由配对比较方法确定的 SOC 存量变化，使用术语 ΔSOCABS 表示使用 SOC 存量差异法计算的存量变化。我们编制了一个数据集，其中包含 700 多条关于 SOC 变化率的记录，代表 12 种碳农业实践。收集覆盖作物 （0.40 ± 0.32）、有机改良剂 （0.52 ± 0.47 和 0.38 ± 0.37 当对照分别为未施肥或液体有机改良剂时）、作物残茬维持 （0.14 ± 0.06）、改良轮作 （0.21 ± 0.16）、减少土壤扰动 （0.24 ± 0.34）、可造林系统 （0.21 ± 0.08）、有机 （0.9 Mg ± 0.25） 和保护管理 （0.78 ± 0.62） 的 Mg ha 0.16 的平均 ΔSOCREL， 预留（当控制分别为农田或牧场/草地时，为 0.75 ± 0.68 和 -0.39 ± 0.50）、农田转化为永久草地（0.79 ± 0.47）、杨树人工林（在农田或牧场/草地上建立时为 0.25 ± 0.68 和 -0.85 ± 0.53）。仅对有机改良剂、覆盖作物、杨树种植园、保护管理、有机管理和联合碳农业实践检测到 SOC 封存，我们估计其 ΔSOCABS 的中位数在 0.32 和 0 之间。96 毫克碳 ha-1 yr-1 在 0-30 厘米处。在农田转为短轮伐林业的 0–30 cm 土壤深度观察到的 ΔSOCABS 导致 C 增加，而当对照为草地时观察到负值。农田转化为永久性草地或牧场在 0-30 和 0-90 和 0-100 cm 土壤深度显示出正 ΔSOCREL。减少土壤扰动 0-50 cm 土壤深度的全土壤剖面评估完全抵消了 0-30 和 0-40 cm 土壤深度表土中发现的任何 SOC 储量增加，因此没有净气候效益。保护管理、有机管理以及将覆盖作物与有机改良作物相结合是将耕地从 C 源转移到净汇的最有效策略，0-30 厘米土壤深度的中位 ΔSOCABS 分别为 0.63、0.91 和 0.96 Mg C ha-1 yr-1。永久性草原和牧场受到任何类型的土地利用变化的负面影响，至少在表层土壤中是这样。耕地撂荒后的自然生态演替（留存 20 年）或耕地转为杨树人工林和草地，在 0–30 cm 处，相对土壤有机碳储量年增加量分别增加 1.08、0.77 和 0.33，而在评估底土时，净气候效益仍不清楚。