Fig. 2. Relationship between different measures of degree of phosphorus saturation (DPS). The DPS is estimated as the ratio of either Olsen (P_Ols) or Mehlich 3 (P_M3)–extractable P to P sorption indices. Ca_M3, Mehlich 3–extractable Ca; (Ca + Mg)_M3, the sum of Mehlich 3–extractable Ca and Mg; P₁₅₀, P sorption index at 150 mg L^–1 of added P; ES_max, estimated Langmuir adsorption.