Grass barrier and vegetative filter strip effectiveness in reducing runoff, sediment, nitrogen, and phosphorus loss

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, NO3-N, NH4-N, particulate P, and PO4-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.