Evaluation of soil quality of different land use types in the southern Tibetan Plateau

In order to clarify the basic characteristics of soil quality in the southern Tibetan Plateau, we collected soil samples from four typical land use types (grassland, plowland, woodland, and shrubland) in this region, measured the relevant basic physicochemical indicators of soil, screened the minimum data set indicators using principal component analysis, and applied the soil quality index (SQI) method to quantitatively evaluate soil quality. The results showed that the land use practices had significant effects on the physical and chemical properties of soil, with saturated hydraulic conductivity as an extremely sensitive indicator, conductivity, total nitrogen, organic matter, and sand particles as highly sensitive indicators, and pH, bulk density, silt particles, and clay particles as moderately sensitive indicators. The minimum data set for soil quality evaluation consisted of total nitrogen, silt particles, clay particles, and electrical conductivity in the southern Tibetan Plateau, and was able to accurately represent the soil quality information in the region (P < 0.01). The SQI calculated from the minimum data set indicated a trend of woodland > grassland > plowland > shrubland, with the soil quality of woodland being significantly higher than that of the other three land use types (P < 0.05). These evaluation results can provide important reference values for rational land use and ecological protection in the southern Tibetan Plateau.