The data comes from the harmonized world soil database version 1.2 (hwsd) built by FAO and IIASA The data source in China is the 1:1 million soil data provided by Nanjing Soil Institute of the second national land survey. The adopted soil classification system is mainly fao-90.  

 unique verification identifier of core soil system unit:   

 MU_ Global-hwsd database soil mapping unit identifier, connecting GIS layers.   

 MU_ Source1 and mu_ Source2 - source database mapping unit identifier   

 SEQ - sequence of soil units in the composition of soil mapping units;  

 the soil classification system uses fao-7 classification system or fao-90 classification system (su_sym74 resp. Su_sym90) or fao-85 (su_sym85)  

 the main fields of the soil attribute table include:   

 ID (database ID)   

 MU_ Global (soil unit identifier) (global)   

 SU_ Symbol soil mapping unit   

 SU_ Sym74 (fao74 classification);   

 SU_ Sym85 (fao85 classification);   

 SU_ Sym90 (soil name in FAO 90 soil classification system);   

 SU_ Code soil mapping unit code   

 SU_ Code74 name of soil unit   

 SU_ Soil unit name   

 SU_ Code90 soil unit name drainage (19.5);   

 REF_ Depth (soil reference depth);   

 AWC_ CLASS(19.5);   

 AWC_ Class (soil available water content);  

 Phase1: real;   

 Phase2: string (soil phase);  

 roots: string (depth classification of obstacles to the soil bottom);   

 SWR: string (soil water content characteristics);   

 ADD_ Prop: real (specific soil type related to agricultural use in soil unit);   

 T_ Texture (top soil texture);   

 T_ Gravel: real (volume percentage of top gravel);   

 T_ Sand: real (top sand content);   

 T_ Sit: real (content of silty sand on the surface);   

 T_ Clay: real (clay content in the top layer);   

 T_ USDA_ Tex: real (top USDA soil texture classification);   

 T_ REF_ Bulk: real (top soil bulk density);   

 T_ OC: real (top organic carbon content);   

 T_ PH_ H2O: real (top pH);   

 T_ CEC_ Clay: real (cation exchange capacity of top cohesive layer soil);   

 T_ CEC_ Soil: real (cation exchange capacity of top soil);   

 T_ BS: real (top basic saturation);   

 T_ TEB: real (top exchangeable base);   

 T_ CaCO3: real (top carbonate or lime content);   

 T_ CaSO4: real (top sulfate content);   

 T_ ESP: real (top exchangeable sodium salt);   

 T_ ECE: real (top conductivity);   

 S_ Gravel: real (volume percentage of bottom gravel);   

 S_ Sand: real (bottom sand content);   

 S_ Sit: real (bottom silt content);   

 S_ Clay: real (bottom clay content); S_ USDA_ Tex: real (USDA soil texture classification of bottom layer);   

 S_ REF_ Bulk: real (bulk density of underlying soil);   

 S_ OC: real (bottom organic carbon content);   

 S_ PH_ H2O: real;   

 S_ CEC_ Clay: real (cation exchange capacity of soil in bottom cohesive layer);   

 S_ CEC_ Soil: real (cation exchange capacity of underlying soil);   

 S_ BS: real (basic saturation of bottom layer);   

 S_ TEB: real (bottom exchangeable base);   

 S_ CaCO3: real (bottom carbonate or lime content);   

 S_ CaSO4: real (bottom sulfate content);   

 S_ ESP: real (exchangeable sodium salt at the bottom);   

 S_ ECE: real (bottom conductivity);   

 the database is divided into two layers, in which the top layer (T) soil thickness is (0-30cm) and the bottom layer (s) soil thickness is (30-100cm).