Fig. 2. Path diagram for the relationship between soil properties and P adsorption by soil. The direct effects (P_ij) of soil properties on P adsorption maxima (S_max) are represented by single-headed arrows while the indirect effects (r_ijP_ij) of soil properties are shown by double-headed arrows. Subscript designations for soil properties and P adsorption are identified numerically as follows: (1) pH = soil pH; (2) clay = clay content; (3) OC = organic carbon content; (4) Al_ox = acid ammonium oxalate extractable Al and Al_M3 = Mehlich-3 extractable Al; (5) Fe_ox = acid ammonium oxalate extractable Fe and Fe_M3 = Mehlich-3 extractable Fe; (6) Ca_M3 = Mehlich-3 extractable Ca; (7) Mg_M3 = Mehlich-3 extractable Mg; and (8) S_max = P adsorption maxima.