Grass Barriers for Reduced Concentrated Flow Induced Soil and Nutrient Loss

Vegetative filter strips (FS) perform poorly for reducing losses of sediment and nutrients in concentrated flow. Stiff‐stemmed grass barriers (B‐FS) above the FS may be a companion treatment to improve the FS performance. This study evaluated the effectiveness of warm‐season switchgrass (Panicum virgatum L.) barriers planted above fescue (Festuca arundinacea Schreb.) FS in reducing runoff water, sediment, N, and P losses in concentrated flow from an Aeric Vertic Epiaqualf on a 5% slope. Simulated rainfall was applied on plots consisting of a 1.5‐m‐wide by 8‐m‐long pollutant source area with an artificially constructed channel to concentrate surface runoff. The source area was bounded downslope by either an 8‐m long fescue FS or 0.7 m of active or dormant barrier above a 7.3‐m‐long fescue FS. The B‐FS treatment also reduced sediment loss by 91% while the FS reduced sediment by only 72% (P < 0.01). The B‐FS also reduced sediment loss by 90%, whereas FS reduced sediment only 60% when inflow was added to the plots. The B‐FS trapped 4.9 times more organic N, 2.3 times more NH4–N, and 3.7 times more particulate P than FS at 0.7 m (P < 0.01). Sediment and nutrient trapping increased significantly with FS length. Switchgrass barriers above the FS dispersed and temporarily ponded concentrated runoff, enabling increased sediment deposition. Barriers may be a potential conservation strategy for rehabilitation of lands affected with concentrated flow where traditional practices are inadequate.