Evaluation of Soil Health of Panax notoginseng Forest Plantations Based on Minimum Data Set

Healthy soil serves as the fundamental basis for sustainable Panax notoginseng (Burkill) F.H. Chen ex C.Y. Wu & K.M. Feng cultivation in understory systems. Current management practices have raised concerns about potential soil degradation and ecological imbalance. To comprehensively assess the soil health status, this study investigated typical understory P. notoginseng plantations in the subtropical mountain monsoon region of western Yunnan. By analyzing 29 soil physical, chemical, and biological indicators, we constructed a Minimum Data Set (MDS) using Principal Component Analysis to evaluate soil health and identify major constraints. The results showed that the MDS for soil health assessment consisted of 11 key indicators: acid phosphatase, fungal ACE index, organic matter, total nitrogen, sucrase, fungal Simpson index, fine sand, non-capillary porosity, silt content, bulk density, and microbial biomass nitrogen. Using both linear and non-linear scoring functions, the Soil Health Index (SHI) calculated based on the MDS showed a significant positive correlation with the SHI derived from the Total Data Set (TDS) (linear scoring: R2 = 0.43, p < 0.001; non-linear scoring: R2 = 0.305, p < 0.001). This indicates that the MDS captures a substantial and significant portion of the variation explained by the TDS and can serve as a practical and simplified alternative for soil health evaluation in this cultivation system. Based on the MDS, the SHI values obtained using linear and non-linear scoring functions ranged from 0.53 to 0.72 and 0.48–0.59, with mean values of 0.62 and 0.51, respectively, indicating moderate soil health status in the study area. Significant differences in SHI were observed across planting durations and seasons (p < 0.05), with two-year-old plantations showing notably better soil health indices than three-year-old plantations, particularly during the rainy season. The main constraints identified in understory P. notoginseng plantations included microbial community degradation, nutrient imbalance, and physical structural deterioration. Implementing scientific soil management strategies such as optimized rotation cycles, organic amendment applications, and microbial community regulation can effectively mitigate these soil constraints, enhance soil health, and promote the sustainable development of understory P. notoginseng cultivation.