Incorporating trees into agricultural systems, including grasslands, increases the soil organic carbon sequestration and contributes to climate change mitigation. Site preparation for tree establishment is a common practice that can involve a variety of techniques and agricultural implements such as subsoiling. This study aimed to evaluate the long-term effects of subsoiling on soil organic carbon (SOC) concentrations and stocks in a Mediterranean grassland afforested with holm oaks 22 years ago and now converted into a Dehesa agroforestry system. The study was conducted in a dehesa farm in Southwest Spain. Soil samples were taken at six depths under 10 tree canopies within and outside the original subsoiling line. Subsoiling significantly decreased SOC concentration. Mean SOC concentration in the first 20 cm was 30% lower at the subsoiling line. SOC stocks for the first 60 cm were 2660 g m⁻² within the subsoiling line and 4320 g m⁻² outside the line. There was a clear reduction in SOC concentration and stock with increasing depth. Root abundance and deeper rooting increased with subsoiling but did not translate into sufficient carbon accumulation in the soil, which is moderate even after 22 years. This study reveals that, in the long term, there is a trade-off in CO₂ sequestration between tree planting and soil subsoiling, highlighting the need for further research into the potential benefits and detriments of subsoiling.

将树木纳入农业系统（包括草地）可增加土壤有机碳固存，并有助于缓解气候变化。植树的场地准备是一种常见的做法，可能涉及多种技术和农具，例如深松。本研究旨在评估深松对地中海草原土壤有机碳 (SOC) 浓度和储量的长期影响，该草原在 22 年前种植了圣栎，现在已转变为 Dehesa 农林复合系统。该研究是在西班牙西南部的一个 dehesa 农场进行的。在原始深松线内外的 10 个树冠下的六个深度采集土壤样本。深松显着降低了 SOC 浓度。前 20 厘米的平均 SOC 浓度在深松线处低 30%。^-2在深松线内，4320 g m ^-2在线外。随着深度的增加，SOC 浓度和储量明显减少。根系丰度和更深的根系随着深松而增加，但并没有转化为土壤中足够的碳积累，即使在 22 年后也是适度的。这项研究表明，从长远来看，植树和土壤深松之间存在 CO _{2封存的权衡，突出表明需要进一步研究深松的潜在​​益处和危害。}