Abstract. Increasing soil organic carbon is promoted as a negative emission technology for the agricultural sector with a potential co-benefit for climate adaptation due to increased soil water retention. Field-scale hydrological models are powerful tools for evaluating how the agricultural systems would respond to the changing climate in upcoming years and decades, for predicting impacts, and for looking for measures that would help decrease drought-driven crop stress under current and future climatic conditions. We quantified how different levels of soil organic carbon (SOC) additions at varied soil depths are expected to influence drought-induced transpiration reduction (Treddry) in maize cultivated in Switzerland. Parameterization of the model based on a pedotransfer function (PTF) was validated against soil moisture data from a long-term lysimeter experiment with a typical Swiss soil, and the model was subsequently applied under climate forcing between 1981 until 2099, representative of three distinct climatic sites of Switzerland. We used the same PTF to indirectly assess the effects of SOC additions at different depths on soil hydraulic properties. We found a threshold in both the added amount of SOC (2 % added) and the depth of sequestering that SOC (top 65 cm), beyond which any additional benefit appears to be substantially reduced. However, adding at least 2 % SOC down to at least 65 cm depth can reduce Treddry in maize, i.e. increase transpiration annually but mostly at the onset of summer drought, by almost 40 mm. We argue that SOC increases in subsoils can play a supporting role in mitigating drought impacts in rain-fed cropping in Switzerland.

中文翻译：

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在干旱开始时将碳封存在地下有利于作物蒸腾

摘要。增加土壤有机碳作为农业部门的负排放技术得到推广，由于土壤保水能力的增加，对气候适应具有潜在的共同效益。田间规模的水文模型是评估农业系统如何应对未来几年和几十年气候变化、预测影响以及寻找有助于减少当前和未来气候条件下干旱驱动的作物压力的措施的有力工具。 。我们量化了不同土壤深度的不同水平的土壤有机碳（SOC）添加量对瑞士种植的玉米中干旱引起的蒸腾减少（Treddry）的影响。基于 Pedotransfer 函数 (PTF) 的模型参数化根据典型瑞士土壤的长期蒸渗计实验的土壤湿度数据进行了验证，随后该模型在 1981 年至 2099 年间的气候强迫下应用，代表了三种不同的气候瑞士的景点。我们使用相同的 PTF 来间接评估不同深度添加 SOC 对土壤水力特性的影响。我们发现 SOC 的添加量（添加 2%）和 SOC 的隔离深度（顶部 65 厘米）都有一个阈值，超过该阈值，任何额外的好处似乎都会大大降低。然而，在至少 65 厘米深度添加至少 2% 的 SOC 可以减少玉米的 Treddry，即每年增加蒸腾量，但主要是在夏季干旱开始时增加近 40 毫米。我们认为，地下土壤有机碳的增加可以在减轻瑞士雨养作物的干旱影响方面发挥支持作用。