Accurate soil organic carbon content estimation is critical as a proxy for carbon sequestration, and as one of the indicators for soil health. Here, we collected 497 soil samples during 2015 and 2019, as well as five environmental covariates (organic carbon (OC) input from the crops, normalized difference vegetation index (NDVI), elevation, clay content and precipitation) at a resolution of 30 m. We then aggregated these to represent agricultural fields and compiled a soil organic carbon (SOC) content map for the agricultural soils of Wallonia using Gradient Boosting Machine. We calculated OC input from both main crops and cover crops for each individual field. As the cover crops do not occur in the agricultural census, we identified cover crops based on long time-series of NDVI values obtained from the Google Earth Engine platform. The quality of the SOC predictions was assessed by validation data and we obtained an R² of 0.77. The Empirical Mode Decomposition indicated that OC input and NDVI were the dominant factors at field scale, whereas the remaining covariates determined the distribution of SOC at the scale of the entire Walloon region. The SOC map showed an overall northwest to southeast trend i.e. an increase in SOC contents up to the Ourthe river followed by a decrease further to the South. The map shows both regional trends in SOC and effects of differences in land use and/or management (including crop rotation and frequency of cover crops) between individual fields. The field-scale map can be used as a benchmark and reference to farmers and agencies in maintaining SOC contents at an appropriate level and optimizing decisions for sustainable land use.

准确的土壤有机碳含量估算作为碳固存的代表和作为土壤健康的指标之一至关重要。在这里，我们在 2015 年和 2019 年期间收集了 497 个土壤样本，以及 5 个环境协变量（作物的有机碳 (OC) 输入、归一化植被指数 (NDVI)、海拔、粘土含量和降水），分辨率为 30 m . 然后，我们将这些汇总以代表农田，并使用 Gradient Boosting Machine 编制了瓦隆农业土壤的土壤有机碳 (SOC) 含量图。我们计算了每个单独田地的主要作物和覆盖作物的 OC 输入。由于农业普查中没有覆盖作物，我们根据从谷歌地球引擎平台获得的长期 NDVI 值确定了覆盖作物。0.77 中的^2个。经验模式分解表明 OC 输入和 NDVI 是田间尺度的主导因素，而其余协变量决定了整个 Walloon 地区尺度上 SOC 的分布。SOC 地图显示整体呈西北向东南趋势，即直到Ourthe 河SOC 含量增加，然后进一步向南减少。该地图显示了土壤有机碳的区域趋势以及各个田地之间土地利用和/或管理（包括轮作和覆盖作物的频率）差异的影响。田间尺度地图可用作农民和机构的基准和参考，以将 SOC 内容保持在适当的水平并优化可持续土地利用的决策。