The purpose of vegetated filter strips (VFS) is to serve as a pollutant filter between aquatic environments and their watersheds. Soil erosion will decrease once VFS are installed and sedimentation and infiltration of runoff within VFS will reduce pollutant loads to the adjacent water body. However, VFS are not effective at controlling all pollutants, particularly those dissolved in runoff waters. In agricultural landscapes, if VFS soils are high in phosphorus (P), they can act as a pollutant source, and not a sink. Therefore, it is important to understand how soil properties impact the pollution prevention value of VFS. Consequently, the Riparian Ecosystem Management Model (REMM) was used to predict landscape conditions that preclude the use of VFS for controlling nonpoint source P pollution in settings when dissolved P is a major component of total P loss. Using agricultural soil and runoff parameters representative of the conditions found in the Mid Atlantic Coastal Plain region of the United States, movement of P was modeled through 11 m VFS. In this region, over-fertilization and manuring has saturated many soils with P, and most of the P buildup has occurred in topsoil horizons (<20 cm). Previous research has shown that soil P sorption capacity can be increased five to ten fold by deep tillage of VFS soils to 45 cm; therefore losses of dissolved P can be decreased by a simple, one-time best management practice. Soil P concentrations and P sorption capacity were varied in REMM, based on data from our laboratory and field studies, to represent the impact of deep tillage on P movement through VFS. Output data were compared to results from field monitoring of dissolved P in VFS soils and used to make predictions of landscape conditions in which VFS will act as a source or a sink for dissolved P.