To clarify the adsorption characteristics of phosphate in facility vegetable field soil and its threshold for loss risk, this study investigated topsoils (0-30 cm) and subsoils (30-60 cm) from solar greenhouses with cultivation durations of 1, 10, and 20 years, as well as plastic greenhouses with 5 and 15-year cultivation histories in Shouguang City, Shandong Province, to analyze of phosphorus adsorption characteristics and quantify the environmental risk thresholds for phosphorus leaching. The results showed that the maximum phosphorus adsorption capacity (Q_max) initially increased then decreased with cultivation duration. This trend correlated significantly with the variations in silt content and calcium carbonate concentration. Both adsorption affinity constant (K) and phosphorus buffering capacity (PBC) demonstrated consistent declines with extended cultivation, showing higher values in subsoil than topsoil. Conversely, phosphorus saturation degree (DPS) displayed an inverse relationship with these parameters. Organic matter content and pH emerged as primary influencing factors of soil-phosphate binding capacity through correlation analysis. Environmental risk analysis established critical thresholds for phosphorus loss at 68.7 mg/kg (risk threshold) and 335.6 mg/kg (control threshold), based on quantitative relationships between available phosphorus, PBC, and DPS. Notably, phosphorus leaching risk escalated with cultivation duration, with subsoil showing unignorable phosphorus loss risk despite their higher adsorption capacity.