Soil erosion is a widespread phenomenon threatening the sustainability of agricultural production in the South-Kivu highlands (eastern D.R. Congo), as is the case in other cultivated areas of the East-African highlands. However, quantitative estimates of soil erosion on farm are scarce. To address this, the extent of erosion and associated explanatory factors were studied in two representative watersheds across a wide range of cropping systems and soil characteristics. Rill and gully erosion volumes were measured every 2 weeks in 90 fields by the transect methods during four successive long (SA) and short (SB) rainy seasons (2015–2017). Additionally, field characteristics and rainfall were collected. Results show that the average soil loss rate was significantly different between seasons, with rates of 3.1 and 1.9 mm in season A-2015, 1.8 and 2.7 mm in season B-2016, 2.2 and 3.3 mm in season A-2016 and 3.2 and 3.8 mm in Season B-2017 for minimum rill (damage area) and gully erosion (whole field), respectively. As a result of differences both in natural factors (e.g., precipitation and slope steepness) and management conditions (cropping systems and soil cover) across farmers' fields, there was a large variability in cumulative soil erosion rates across fields, from 0.03 to 18 mm for minimum rill erosion and from 0.13 to 11.7 mm for gully erosion rates over the 4 seasons. For 41% of fields, rill erosion rates are higher than the tolerable soil loss generally set at 12.5 t/ha/year (or 1 mm/year) for the most fertile soils. Low minimum rill erosion rates tended to be associated with high pH, sum of bases and effective CEC, while high erosion rates were associated with high topsoil depth in both watersheds. Cassava-based cropping systems tended to be associated with high rill erosion rates, while higher rainfall increased both rill and gully erosion rates. Overall, the very high measured rill erosion rates suggest the urgent need for implementation of erosion control strategies. The results could be used to prioritize sites at risk of water erosion at the small watershed scale in order to install mitigation measures.

与东非高地的其他耕地一样，土壤侵蚀是一种普遍现象，威胁着南基伍高地（刚果民主共和国东部）农业生产的可持续性。然而，对农场土壤侵蚀的定量估计很少。为了解决这个问题，我们在两个具有代表性的流域中研究了侵蚀程度和相关的解释因素，这些流域具有广泛的种植系统和土壤特征。在连续四个长 (SA) 和短 (SB) 雨季 (2015-2017) 期间，通过横断面方法每 2 周测量 90 个田地的细沟和沟壑侵蚀量。此外，还收集了田间特征和降雨量。结果表明，平均土壤流失率在季节之间存在显着差异，A-2015、1.8和2季的流失率分别为3.1和1.9 mm。B-2016 季节为 7 毫米，A-2016 季节为 2.2 和 3.3 毫米，B-2017 季节为 3.2 和 3.8 毫米，分别用于最小细沟（损坏区域）和沟壑侵蚀（整个场地）。由于农民田间自然因素（如降水和坡度）和管理条件（种植制度和土壤覆盖）的差异，田间累积土壤侵蚀率存在很大差异，从 0.03 到 18 毫米对于最小的细沟侵蚀和 0.13 到 11.7 毫米的 4 个季节的沟壑侵蚀率。对于 41% 的田地，细沟侵蚀率高于通常为最肥沃的土壤设定的 12.5 吨/公顷/年（或 1 毫米/年）的可容忍土壤流失率。低最小细沟侵蚀率往往与高 pH 值、碱总和和有效 CEC 相关，而两个流域的高侵蚀率与高表土深度有关。以木薯为基础的种植系统往往与高细沟侵蚀率有关，而较高的降雨量增加了细沟和沟渠侵蚀率。总体而言，测量到的非常高的细沟侵蚀率表明迫切需要实施侵蚀控制策略。结果可用于在小流域尺度上优先考虑面临水蚀风险的地点，以便采取缓解措施。