The data were obtained from the Harmonized World Soil Database version 1.2 (HWSD) constructed by the Food and Agriculture Organization of the United Nations (FAO) and the International Institute for Applied Systems (IIASA), Vienna. The data source in China is the 1:1 million soil data provided by the Nanjing Soil Survey of the Second National Land Survey. The soil classification system used was mainly FAO-90.

Unique validation identifier for core soil system units:

MU_GLOBAL-HWSD database soil mapping unit identifier with GIS layers connected.

MU_SOURCE1 and MU_SOURCE2- Source database mapping unit identifiers.

SEQ-Soil unit sequence in the soil mapping unit composition;

The soil classification system utilizes the FAO-7 classification system or the FAO-90 classification system (SU_SYM74 resp. SU_SYM90) or FAO-85 (SU_SYM85).

The main fields of the soil properties 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 names in the FAO90 soil classification system);

SU_CODE Soil mapping unit code;

SU_CODE74 Soil unit name;

SU_CODE85 Soil unit name;

SU_CODE90 Soil unit name; DRAINAGE(19.5);

REF_DEPTH (soil reference depth);

AWC_CLASS(19.5);

AWC_CLASS (effective soil water content);

PHASE1: Real (soil phase);

PHASE2: String (soil phase);

ROOTS: String (depth classification to the bottom of the soil where barriers exist);

SWR: String (soil water content characteristics);

ADD_PROP: Real (specific soil type in the soil unit that is relevant for agricultural use);

T_TEXTURE (top soil texture);

T_GRAVEL: Real (top layer gravel volume percentage);

T_SAND: Real (top layer sand content);

T_SILT: Real (top layer silt content);

T_CLAY: Real (top clay content);

T_USDA_TEX: Real (top layer USDA soil texture classification);

T_REF_BULK: Real (top soil bulk weight);

T_OC: Real (top layer organic carbon content);

T_PH_H2O: Real (top layer pH);

T_CEC_CLAY: Real (cation exchange capacity of the top clay layer soil);

T_CEC_SOIL: Real (cation exchange capacity of the top soil layer);

T_BS: Real (basic saturation of the top layer);

T_TEB: Real (top layer exchangeable salt base);

T_CACO3: Real (carbonate or lime content of the top layer);

T_CASO4: Real (top layer sulfate content);

T_ESP: Real (top exchangeable sodium salt);

T_ECE: Real (top layer conductivity);

S_GRAVEL: Real (bottom layer gravel volume percentage);

S_SAND: Real (bottom sand content);

S_SILT: Real (bottom silt content);

S_CLAY: Real (subgrade clay content); S_USDA_TEX: Real (subgrade USDA soil texture classification).

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