Objective To investigate the soil physicochemical properties and fruit quality in gonggan (Citrus reticulata ‘Gonggan’) orchards, and clarify the relationships between soil physicochemical properties and fruit quality indicators, aiming to provide a scientific basis for nutrient regulation and fertilization strategies in these orchards.

Method Ten representative orchards were selected in Deqing County, Guangdong Province. Soil physicochemical properties and fruit quality indicators were measured, respectively. Multivariate analysis methods, including correlation analysis, regression analysis, and linear programming, were applied to identify the primary soil nutrient factors those influence fruit quality.

Result The soil in gonggan orchards was generally acidic. The medium elements such as Ca and Mg were predominantly deficient, whereas soil organic matter was generally abundant, and microelements such as Fe and Cu were at appropriate or abundant levels. Correlation analysis result indicated that fruit transverse diameter was significantly and positively correlated with exchangeable Mg content; Titratable acid content was significantly and positively correlated with soil organic matter, total N, and cation exchange capacity; Vitamin C content was significantly and negatively correlated with exchangeable Na, Ca, and Mg contents. Multivariate analysis result demonstrated that the key soil factors affecting the quality of gonggan fruit quality included pH as well as total N, alkali-hydrolyzable N, exchangeable Ca, exchangeable Mg, available Mn, available Cu, and available B contents. Comprehensive evaluation using the entropy-weighted TOPSIS method indicated that Lijia Farm exhibited the optimal fruit quality, while the overall fruit quality from the Huilong Town production area was relatively superior. When the quality of gonggan is best, the theoretical optimal ranges of soil physicochemical indicators were: pH 5.50–6.50, total N content 1.40–1.50 g·kg⁻¹, alkali-hydrolyzable N content 200 mg·kg⁻¹, exchangeable Ca content 1 000 mg·kg⁻¹, exchangeable Mg content 100 mg·kg⁻¹, available Mn content 5 mg·kg⁻¹, available Cu content 1 mg·kg⁻¹, and available B content 0.50 mg·kg⁻¹.

Conclusion Soil management in Deqing gonggan orchards shall focus on the application of alkaline fertilisers to mitigate soil acidification, and optimize the supply of N, Ca, and Mg.