Minimum data set Quality control 2 Red soils 2 Soil quality index 2 Soils qualities 2 red soil 2 soil organic matter 2 soil quality 2 China 1 Compaction 1 Corn cultivation 1 Corn fields 1 Cultivated-layer soil quality 1 Cultivation 1 Deforestation 1 Digital storage 1 Forest soil 1 Forest soils 1 Hydraulic conductivity 1 Indicator indicator 1 Indicator threshold 1 Iron 1 Land use 1 Land-use change 1 Landuse change 1 Maize cultivation 1 Memberships function 1 Nitrogen 1 Organic carbon 1 Principal component analysis 1