Riparian zone impact on phosphorus movement to a Coastal Plain black water stream

ABSTRACT:

Riparian zones are an important conservation practice because they can decrease the entry of sediments and nutrients into sensitive aquatic ecosystems. We evaluated the effectiveness of a Coastal Plain riparian zone in decreasing the movement of phosphorus (P) into a black water stream from an overloaded swine manure spray field. Soil P concentrations (Mehlich 3 P, M3P; and total P, TP) were measured in a spray field, grass strip, mid-riparian, and stream edge continuum. Dissolved P (DP) was measured in ground water wells located in the spray field, grass strip, and stream edge and in in-stream grab samples. The spray field and grass strip areas had high soil M3P concentrations. Low M3P concentrations were detected in soils in the mid-riparian and stream edge areas, indicating effective retention of P by the grass strip area. Elevated DP concentrations were detected in the spray field and grass strip wells, while stream edge wells were low. The riparian zone contributed to decreased DP concentrations between the grass strip and stream edge wells. Furthermore, stream grab samples were consistently low in DP concentrations. We conclude that a riparian zone can effectively limit the movement of P-enriched sediments and prevent DP-enriched ground water from entering a local stream, even in a heavily loaded situation.