Soil Health Evaluation for the Main Production Areas of Watermelon and Musk Melon in Xinjiang Based on the Optimization of Minimum Data Set System

In order to systematically evaluate the soil health status of the main watermelon and musk melon production areas in Xinjiang and to establish an optimized soil health assessment framework suitable for arid agroecosystems, this study comprehensively analyzed 156 soil samples collected from eight major production regions in Xinjiang, China. Using principal component analysis (PCA), a minimum data set (MDS) comprising organic matter (OM), total potassium (TK), total phosphorus (TP), ammonium nitrogen (AN), iron (Fe), and chromium (Cr) was screened from 18 physicochemical and heavy metal parameters. Eight soil health indices were constructed by integrating linear (L) and nonlinear (NL) scoring functions with two integration approaches-soil health index (SHI) and integrated health index (IHI). The optimal method for assessing soil health in Xinjiang's main watermelon and musk melon production areas was identified, and soil resilience was quantified using a sensitivity-resistance framework. The results show that the study area is characterized by widespread soil degradation, including nutrient depletion (OM and total nitrogen at Grade IV) and severe salinity stress (mean pH =8.38). Although heavy metal concentrations remained below contamination thresholds, enrichment of chromium (Cr) and nickel (Ni) (1.06-3.93 times background values) indicated anthropogenic inputs. The selected optimal model, MDS-NL-IHI, exhibited strong discriminatory power, with index values ranging from 0.39 (Hetan) to 0.58 (Aksu), reflecting significant regional heterogeneity (P<0.05). The primary limiting factor was OM deficiency (contribution: 31.66%), while TP, Cr, and AN were identified as sensitivity indicators, and OM, TK, and Fe as resistance indicators. The study has determined that the soil health status of Xinjiang's main watermelon and musk melon production areas is at a "moderately healthy" level. The low organic matter and nutrient content can be improved through appropriate nutrient management practices, such as increased application of organic fertilizers, straw incorporation, and green manure rotation. In addition, each production region can promote soil health and the sustainable development of the melon industry by exploring locally suitable farming practices for Xinjiang melons.