Purpose <p>The Hanjiang Delta faces significant risks of soil quality degradation due to intensive agriculture and rapid urbanization, necessitating a robust evaluation of the soil quality index (SQI). The conventional cumulative frequency method, which relies on normality assumptions to derive membership functions, often introduces distortions when grading non-normal, right-skewed geogenic and environmental data, thereby biasing SQI estimates. This study introduces, for the first time in the Jieyang region, an inflection point method based on logarithmic empirical cumulative distribution function (ECDF). This new method improves the identification of pollution hotspots, crucial for effective soil management in rapidly developing regions.</p> Methods <p>Utilizing 1,327 topsoil samples and 44 indicators (encompassing beneficial, harmful, and essential elements), two SQIs were constructed and compared after weighting using the entropy weight method. Two SQIs were constructed—one using the conventional cumulative frequency method and one using the logarithmic ECDF inflection point method—and statistically and spatially compared.</p> Results <p>The inflection point method yielded a significantly lower mean SQI (0.50) than the cumulative frequency method (0.55). Spatial discrepancies were pronounced, with high-difference zones (ΔSQI &gt; 0.16) concentrated in the Rongjiang alluvial plain (max ΔSQI = 0.1647) and Huilai County coastal plain (max ΔSQI = 0.1953), coinciding with intense human activities (e.g., e-waste sites, intensive farmland) and strongly right-skewed distributions of harmful (Cr, Cd, Hg) and beneficial/essential (P, B) elements. The conventional method diluted high-value anomalies in skewed tails due to normality assumptions. In contrast, the logarithmic ECDF method adapts to the non-normal distribution, capturing these extreme values more accurately. The transformation and maximization of curvature in the logarithmic ECDF improve the detection of pollution hotspots by enhancing the sensitivity to high-concentration, non-normal data, providing more accurate information for remediation and management strategies.</p> Conclusion <p>The logarithmic ECDF inflection point method, through logarithmic transformation and curvature maximization, provides adaptive thresholds that better capture geogenic variation and anthropogenic pollution hotspots. It is more suitable for soil quality assessment in complex deltaic regions and establishes an improved, distortion-resistant SQI framework for precise soil management in the Hanjiang Delta. This method has important practical implications for soil management, enabling more accurate identification of pollution hotspots, facilitating targeted remediation efforts, and supporting sustainable land use practices.</p>