Fig. 4From: Improving soil organic carbon mapping in farmlands using machine learning models and complex cropping system informationSpatial distribution of environmental variables. a MAP: mean annual precipitation. b MAT: mean annual temperature. c Soil types. d NDVImean: annual NDVI average. e NDVImax: annual NDVI maximum. f Clay content. g pH. h Silt content. i TN. j TP, and k TKBack to article page