For decades, conservation tillage has been promoted as a measure to increase carbon stocks in arable soils. Since organic farming improves soil quality and soil carbon storage, reduced tillage under organic farming conditions may further enhance this potential. Therefore, we assessed soil organic carbon (SOC) stocks of reduced tillage compared with mouldboard ploughing in nine organic farming field trials in France, Germany, the Netherlands, and Switzerland with the same sampling and analytical protocol. We sampled soil cores until a depth of 100 cm to determine soil carbon stocks that are relevant for climate change mitigation but are often overlooked in tillage studies with shallow sampling depths. The studied field experiments were between 8 and 21 years old and comprised different soil types with clay contents ranging from 10% to 50%. SOC stocks increased with increasing clay-to-silt ratio, precipitation and organic fertiliser input. Across sites, reduced tillage in comparison with ploughing increased SOC stocks in the surface layer (0–10/15 cm) by 20.8% or 3.8 Mg ha⁻¹, depleted SOC stocks in the intermediate soil layers to 50 cm soil depth with a maximum depletion of 6.6% or 1.6 Mg ha⁻¹ in 15/20–30 cm and increased SOC stocks in the deepest (70–100 cm) soil layer by 14.4% or 2.5 Mg ha⁻¹. The subsoil SOC stock increase may be linked to the inherent soil heterogeneity. Cumulative SOC stocks increased by 1.7% or 1.5 Mg ha⁻¹ (0–50 cm, n = 9) and 3.6% or 4.0 Mg ha⁻¹ (0–100 cm, n = 7) by reduced tillage compared with ploughing with estimated mean C sequestration rates of 0.09 and 0.27 Mg ha⁻¹ yr⁻¹, respectively. There was no effect of field trial duration on tillage induced cumulative SOC stocks differences. Under reduced tillage, biomass production was 8% lower resulting in a decrease of crop C input by 6%. However, this reduction may have been outbalanced by increased C inputs from weed biomass resulting from a higher weed incidence in reduced tillage, which warrants further research. Thus, reduced tillage in organic farming has the potential to increase total SOC stocks, while crop management has to be improved to increase productivity.

几十年来，保护性耕作一直被推广为增加可耕土壤中碳储量的措施。由于有机耕作改善了土壤质量和土壤碳储存，在有机耕作条件下减少耕作可能会进一步增强这种潜力。因此，我们在法国、德国、荷兰和瑞士的九个有机农业田间试验中，使用相同的采样和分析方案，评估了与犁耕相比减少耕作的土壤有机碳 (SOC) 储量。我们对土壤核心取样直至 100 厘米的深度，以确定与减缓气候变化相关但在浅取样深度的耕作研究中经常被忽视的土壤碳储量。所研究的田间试验年龄介于 8 至 21 岁之间，包括不同土壤类型，粘土含量介于 10% 至 50% 之间。SOC 储量随着粘土与淤泥比、降水和有机肥投入的增加而增加。在不同地点，与犁耕相比，减少耕作使表层（0-10/15 厘米）的 SOC 储量增加 20.8% 或 3.8 毫克公顷^-1，中间土壤层中的 SOC 储量减少至 50 cm 土壤深度，最大消耗量为 6.6% 或 1.6 Mg ha ^-1在 15/20-30 cm 中，最深（70-100 cm）土壤中的 SOC 储量增加14.4% 或 2.5 Mg ha ^-1。底土 SOC 储量的增加可能与土壤固有的异质性有关。与估计的耕作相比，减少耕作使累积 SOC 储量增加 1.7% 或 1.5 Mg ha ^-1（0-50 cm，n = 9）和 3.6% 或 4.0 Mg ha ^-1（0-100 cm，n = 7） 0.09 和 0.27 Mg ha ^-1 yr ^{-1 的}平均 C 封存率， 分别。田间试验持续时间对耕作引起的累积 SOC 储量差异没有影响。在减少耕作的情况下，生物质产量降低了 8%，导致作物碳输入减少了 6%。然而，这种减少可能被杂草生物量的 C 输入增加所抵消，这是由于减少耕作导致杂草发生率增加，这值得进一步研究。因此，有机农业中减少耕作有可能增加总有机碳储量，同时必须改进作物管理以提高生产力。