Abstract: Objective Establishing vegetation on dry-discharged iron tailings requires a substrate with suitable physical and chemical properties. In the semiarid Zhangxuan mining area, the relation between regional soil conditions and engineering requirements needs to be clarified before grading values can guide substrate improvement. This study aimed to identify the main limitations of tailings and develop a graded assessment that distinguishes observed regional conditions from general and enhanced substrate targets.Methods Surface samples from ten forest, shrubland and grassland reference plots were compared with bare tailings (KA) and naturally colonized tailings (KB). Twelve physicochemical indicators were examined within a framework containing nineteen indicators in four categories. Regional summaries were combined with greening soil requirements and soil contamination screening values. Four common quantitative requirements were used for the general target, and eight were used for the enhanced target. Seven potentially harmful elements were included as risk comparison items but were not measured. Reference distributions were treated as descriptive information rather than plant response thresholds. Structural summaries included ranges, means and quartiles, with leave-one-plot-out calculations used to examine sensitivity to reference composition. Non-capillary porosity was estimated using an assumed particle density of 2.65 g/cm3. Particle-size composition was summarized for nine reference plots after one inconsistent record was excluded; the other indicators for that plot were retained. Results Reference bulk density averaged 1.073 g/cm3, whereas the values in KA and KB were 1.92 and 1.62 g/cm3, respectively, representing increases of 78.9% and 51.0%. Water-stable aggregates larger than 0.25 mm averaged 41.9% in the reference plots, while both tailings samples had reported values of zero. Mean reference organic matter was 2.67%, compared with 0.2% in KA and 0.3% in KB. Reference total nitrogen averaged 1 390 mg/kg, compared with 120 and 200 mg/kg in the two tailings samples. Cation exchange capacity was 4.0 cmol(+)/kg in KA and 12.5 cmol(+)/kg in KB, compared with a reference mean of 21.08 cmol(+)/kg. Both tailings samples failed three of the four common requirements, but the failed items differed: KA had excessive bulk density, low estimated non-capillary porosity and low organic matter, whereas KB had excessive bulk density, low organic matter and a pH above the general greening range. Under the eight enhanced requirements, KA failed six and KB failed five. Vegetation cover in KB was 10%, while organic matter and available nitrogen and phosphorus remained low. The observed presence of vegetation therefore coexisted with substantial substrate limitations. Regional distributions provided additional information for indicators without sufficiently supported grading boundaries, including capillary porosity, water-stable aggregates and total nitrogen. Conclusions The general target identifies basic substrate improvement tasks, while the enhanced target specifies additional nutrient and exchange-capacity requirements. Regional observations help interpret structural and fertility differences. Application of the grading framework requires separate risk testing and evaluation of vegetation performance under field conditions; the framework supports substrate design and staged management in the study area.