Management practices in the inter-row area of olive orchards are undergoing significant transformations. Current regulations and recommendations are increasingly advocating the implementation of temporary spontaneous cover crops (TSCV) mainly to reduce erosion. Existing research has predominantly focused on evaluating the effectiveness of TSCV in mitigating soil erosion in olive orchards, with limited attention given to carbon (C) cycling, despite the potential of TSCV for contributing to the removal of atmospheric CO and in the reduction of eroded carbon. Moreover, the limited number of studies on the effects of TSCV on C cycling have been confined to a few experimental sites and at the short term. This study aimed to assess the potential of TSCV to enhance carbon sequestration and nitrogen retention in rainfed commercial olive orchards under semi-arid conditions. To achieve this, we evaluated the annual aboveground organic carbon input due to TSCV, as well as the stocks of soil organic (SOC) and inorganic (SIC) carbon and total N (STN) in 24 commercial olive groves with calcareous Regosols and calcium Cambisols as the predominant soil types that have implemented TSCV for at least the last 8 years. These were compared with 24 comparable groves with bare soil (BS). Net aboveground annual carbon and CO fixation of the TSCV averaged 125.7 kg C ha y and 460 kg CO ha y, respectively, which are figures relatively low mainly due to the low area covered by the TSCV. After eight years of implementing TSCV, the SOC stocks increased by an average of 2.03 Mg C ha (in the top 30 cm of soil) compared to BS olive orchards. Moreover, SOC content of unprotected (>250 µm) and physically protected (53–250 µm) fractions were 82 and 38 % higher in the TSCV olive farms. Although there was a tendency of lower SIC content in TSCV olive orchards, differences were not significant. The STN content and the potentially mineralizable nitrogen in TSCV farms were on average 26 % and 77 % higher than in BS olive orchards. These findings underscore the potential of TSCV for organic carbon accumulation and nitrogen retention in the soil, contributing to climate change mitigation and soil fertility enhancement. Increasing vegetation coverage and productivity can enhance their effectiveness.

中文翻译：

---

自发覆盖作物是否会增加商业橄榄园土壤有机碳和氮的储量？


橄榄园行间区域的管理实践正在经历重大转变。目前的法规和建议越来越多地提倡实施临时自发覆盖作物（TSCV），主要是为了减少侵蚀。现有的研究主要集中在评估 TSCV 在减轻橄榄园土壤侵蚀方面的有效性，尽管 TSCV 具有促进去除大气 CO 和减少侵蚀碳的潜力，但对碳 (C) 循环的关注有限。此外，关于 TSCV 对 C 循环影响的研究数量有限，仅限于少数实验地点和短期研究。本研究旨在评估 TSCV 在半干旱条件下增强雨养商业橄榄园碳固存和氮保留的潜力。为了实现这一目标，我们评估了 24 个含有钙质 Regosol 和钙 Cambisol 的商业橄榄园中由于 TSCV 导致的年度地上有机碳输入，以及土壤有机碳 (SOC) 和无机碳 (SIC) 以及总氮 (STN) 的储量作为至少在过去 8 年实施 TSCV 的主要土壤类型。将它们与 24 个具有裸露土壤 (BS) 的可比较树林进行了比较。 TSCV 的年地上净碳和 CO 固定量平均分别为 125.7 kg C ha y 和 460 kg CO ha y，这一数字相对较低，主要是由于 TSCV 覆盖面积较小。实施 TSCV 八年后，与 BS 橄榄园相比，SOC 储量平均增加了 2.03 Mg C ha（土壤表层 30 厘米）。此外，TSCV 橄榄农场中未受保护 (>250 µm) 和物理保护 (53–250 µm) 部分的 SOC 含量分别高出 82% 和 38%。 尽管TSCV橄榄园中SIC含量有较低的趋势，但差异并不显着。 TSCV 农场的 STN 含量和潜在矿化氮平均比 BS 橄榄园高 26% 和 77%。这些发现强调了 TSCV 在土壤中有机碳积累和氮保留方面的潜力，有助于减缓气候变化和提高土壤肥力。增加植被覆盖率和生产力可以提高其有效性。