Fig. 2. Apparent sorption isotherms of orthophosphate P in KH₂PO₄–amended soils after 8 wk. Each point represents the mean of three measurements. Lines represent the nonlinear fits to the Langmuir equation. Values in parentheses are NaOAc cation exchange capacity (CEC; cmol_c kg^–1) for each respective soil series. DRP, dissolved molybdate-reactive phosphorus.