Mapping performance of SoilGrids1km — amount of variation explained (from 100%) or purity/kappa for categorical variables — for eight targeted soil properties and two soil classes distributed via SoilGrids1km.

WRB = “World Reference Base”; USDA = “United States Department of Agriculture”.
Amount of variation explained by the models (Eq.5) i.e. kappa statistics for soil types was determined using 5–fold cross-validation.
Mapping performance of SoilGrids1km — amount of variation explained (from 100%) or purity/kappa for categorical variables — for eight targeted soil properties and two soil classes distributed via SoilGrids1km.

WRB即世界土壤资源参比基础（World Reference Base），USDA即美国农业部（United States Department of Agriculture）。本研究采用5折交叉验证（5-fold cross-validation）计算了各模型（公式5）所能解释的变异量，其中针对土壤类型的评价指标为kappa统计量（kappa statistics）。SoilGrids1km的制图性能评估针对8种目标土壤属性与2类通过SoilGrids1km发布的土壤类别展开，评估指标包括可解释变异占比（以100%为基准）以及分类变量的纯度、kappa统计量。