Large-Scale Photovoltaic Farms in the Qinghai Desert: Soil Quality Assessment Methods

Photovoltaic (PV) farms have location-dependent effects on soil, climate, and vegetation. To assess the soil quality status of large-scale PV farms in desert areas, this study was carried out at the Qinghai Gonghe PV farms. The 14 physical and chemical properties of the soil, including soil water content (SWC), bulk density, clay, silt, sand, total nitrogen, total carbon, total phosphorus, total potassium, available nitrogen, available potassium (AK), soil organic matter (SOM), available phosphorus (AP), and pH, in the surface soil (0–0.2 m) under the PV panels, between the panels and the control area, were compared and analyzed. Principal component analysis was used to establish the construction of the minimum data set, and the soil quality index (SQI) was calculated using two scoring methods, linear and nonlinear. The results showed that (1) SWC and clay content were significantly higher (p < 0.05) under the PV panels compared to the control area, and the remaining indicators were not significantly different (p > 0.05). (2) The minimum data set for soil quality evaluation in the study area included SOM, clay content, AP, and AK. (3) The SQI under and between PV panels was higher than the control area under both scoring methods, but the improvement was not significant (p > 0.05). The SQI calculated using the nonlinear scoring based on the minimum data set can more accurately reflect soil quality in the study area, providing information for soil management and decision-making in large-scale PV farms.