Abstract: Interactions between land-use and environmental drivers of soil quality in fragile ecosystems remain insufficiently quantified. The impact of land-use types and environmental factors on soil quality in the Loess Plateau was assessed here using a minimum data-set-based soil quality index. Data were collected from 99 plots across mixed forests, forests, shrublands, and grasslands. Principal component analysis was applied to construct the minimum data set with bulk density, capillary water-holding capacity, soil organic carbon, natural moisture content, and total phosphorus as core evaluation indicators. Using an obstacle factor diagnostic model and partial least squares path modeling, we identified soil moisture as the primary limiting factor. Grassland soil quality was lowest in Wangwazi (0.42), Changcheng (0.47), and Shenmu (0.21), but shrubland and grassland soil quality was highest in Hengshan (0.30, 0.27) and Yuyang (0.42, 0.53) (P < 0.05). These results provide guidance for sustainable land management in ecologically fragile regions.

Key words: Soil quality index, Land use types, Minimum data set, Soil constraints, Water-wind erosion crisscross region