• The study reveals that traditional hazard quotient (HQ) models underestimate ecological risks in agricultural soils, while probabilistic ecological risk assessment (PERA) provides more accurate and site-specific risk characterization.
• PERA incorporates species-specific PNEC, environmental variability, and uncertainty, assigning probabilities to risk estimates, thus offering a superior tiered approach for contaminated farmland management.
• Heavy metal contamination (As, Cd, Cr, Hg, Pb) in the Western Dongting Lake area poses consistently high and unacceptable ecological risks, necessitating urgent soil management and remediation strategies.
• The tiered PERA model provides critical guidance for ecological protection and soil management, highlighting its novelty and practical applicability in contaminated agricultural regions.