Evaluation of cultivability of sloping farmland in Hunan province

Background Sloping farmland is a high-incidence region for soil erosion on cultivated land, so it is essential to evaluate the cultivation of sloping farmlands in Hunan Province based on the current status of its resources. Methods Using GIS technology, this study established a basic database of sloping farmland in Hunan Province. After screening, seven indicators were selected as key evaluation indicators: slope gradient (°), soil layer thickness (cm), soil texture, pH, cation exchange capacity (CEC, cmol(+)/kg), organic matter content (g/kg), and soil erosion severity. Based on the limiting factor evaluation method, the cultivation suitability of sloping farmland across the province was systematically assessed. Results The results show that among 3,754.51 km² of slope farmland in the province (10.08% of the total farmland area), the unsuitable area reached 1,502.66 km² (40.02%). Analysis of limiting factors indicates that the main constraints include excessively high gravel fraction, insufficient CEC, and overly steep slopes. Specifically, areas with slopes exceeding 25° covered 311.77 km²; areas with gravel content greater than 15% covered 410.01 km²; and areas with CEC lower than 10 cmol(+)/kg covered 824.08 km². Within the unsuitable cultivated land, the slightly unsuitable category accounted for 62.3%, while the moderately and severely unsuitable land accounted for 24.5% and 13.2%, respectively. Conclusion The findings provide a scientific basis for regional soil erosion prevention and control and for optimizing the land use structure on sloping farmland.