Adding a highly phosphorus (P) retentive material to sandy surface soil such as in the Louisiana coastal plain would be expected to reduce loss of P in runoff and sub-surface flow. In the later case, barriers of the mixed material may intercept and retard off-site migration of P. The sorption of phosphate in Ruston soil (fine-loamy, siliceous, thermic Typic Paleudults), bauxite residue and mixtures of soil and this P retentive material, were described by Langmuir isotherms and showed markedly increased retention of phosphate with added bauxite residue. Retardation of phosphate during steady-state, saturated transport through packed columns of Ruston soil mixed with bauxite residue was generally consistent with the batch isotherm data, supporting potential use of this material as an amendment to limit sub-surface, lateral transport.