Grass Barrier and Vegetative Filter Strip Effectiveness in Reducing Runoff, Sediment, Nitrogen, and Phosphorus Loss

Abstract

Addition of switchgrass ( Panicum virgatum ) barriers to vegetative filter strips (FS) shows potential as conservation practice. This study evaluates the comparative effectiveness of three conservation practices in reducing runoff, sediment, N, and P losses from 1.5‐ by 16‐m plots on an Aeric Epiaqualf. Three practices compared are a traditional fescue ( Festuca arundinacea ) filter strip (Fescue‐FS), a switchgrass barrier in combination with the Fescue‐FS (B‐Fescue‐FS) and a switchgrass barrier in combination with a native grass and forbs species filter strip (B‐Native‐FS). This study also predicts transport of sediment, N, and P in Fescue‐FS and B‐Fescue‐FS. Fescue‐FS and B‐Fescue‐FS of equal widths (0.7 m) significantly reduced runoff and sediment transport as compared with a continuous cultivated fallow (CCF) treatment, but B‐Fescue‐FS was more effective for reducing runoff ( p < 0.05) and sediment ( p < 0.01) transport. B‐Fescue‐FS was also more effective than Fescue‐FS for reducing losses of organic N, NO 3 –N, NH 4 –N, particulate P, and PO 4 –P ( p < 0.01). Fescue‐FS and B‐Native‐FS were equally effective for reducing runoff, sediment, and nutrient loss. Effectiveness of FS increased with distance with 18% of runoff, 92% of sediment, and 71% of nutrient leaving the source area being reduced in the first 4 m of the FS. An equation to predict sediment associated with runoff ponding above barriers explained approximately 70% of the variability between measured and predicted values of sediment, organic N, and particulate P transport. Combination of switchgrass barriers with FS is an effective alternative to Fescue‐FS alone for reducing sediment and nutrients in runoff.