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ARS Home » Midwest Area » Columbia, Missouri » Cropping Systems and Water Quality Research » Research » Publications at this Location » Publication #157100
Title: GRASS BARRIERS FOR REDUCED CONCENTRATED FLOW EROSION

Author
item BLANCO-CANQUI, HUMBERTO - UNIV OF MO
item GANTZER, C - UNIV OF MO
item ANDERSON, S - UNIV OF MO
item ALBERTS, EDWARD

Submitted to: Soil Science Society of America Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/7/2004
Publication Date: 11/1/2004
Citation: Blanco-Canqui, H., Gantzer, C.J., Anderson, S.H., Alberts, E.E. 2004. Grass barriers for reduced concentrated flow erosion. Soil Science Society of America Journal. 68:1963-1972.

Interpretive Summary: Filter strips planted along streams to reduce nonpoint-source (NPS) pollution do not work effectively when surface runoff enters the strips as concentrated flow from low points in the topography. Planting narrow, stiff-stem grass barriers immediately above filter strips may be an effective and easily adopted method to intercept concentrated flow and reduce the amount of pollutants being carried. The objective of this study was to compare the effectiveness of a grass barrier-filter strip system in reducing sediment, nitrogen (N), and phosphorus (P)losses relative to a typical filter strip system. Treatments were evaluated by applying simulated rainfall and runoff to small plots containing an artificially constructed channel to concentrate surface runoff. Switchgrass barriers in combination with fescue filter strips retarded concentrated flow and trapped 1.5 times more sediment, 4.9 times more organic N, 3.7 times more particulate P, and 2.3 times more ammonium nitrogen. Another finding was that most of the reduction in sediment, N, and P occurred soon after runoff entered the filter strips, indicating that less land may need to be taken out of crop production than previously thought. The results of this study will benefit conservationists, water quality specialists, and farmers who plan and implement vegetative filter strips to optimize water quality and wildlife benefits.

Technical Abstract: Vegetative filter strips (FS) perform poorly for reducing concentrated flow erosion. Stiff-stemmed grass barriers planted immediately above FS may be a companion treatment to improve the FS performance. This study evaluated the effectiveness of warm season switchgrass (Panicum virgatum) barriers planted above fescue (Festuca arundinacea) filter strips in reducing runoff, sediment, nitrogen (N), and phosphorus (P) losses in concentrated flow from an Aeric Vertic Epiaqualf on a 5% slope. Simulated rainfall at 66 mm/h was applied on plots consisting of a 1.5- by 8-m sediment source area with an artificially constructed channel to concentrate surface runoff. The source area was bounded downslope by either an 8-m long fescue filter strip (FS) or 0.7 m of active or dormant barrier above a 7.3-m long fescue FS. To evaluate treatments with increased sediment source areas, added inflow rates of up to 12.5 L/min were used to simulate larger source areas when the barriers were dormant. Runoff was sampled at 1 m above the downslope edge of the source area and at 0.7, 4, and 8 m in the filter strip to analyze sediment, N, and P concentrations. Active or dormant barriers reduced 10% more runoff than the FS treatment at 0.7 m (P<0.05). Barriers also reduced sediment loss by 91% while the FS reduced sediment by only 72% (P<0.01). When the source area was doubled by adding inflow, barriers reduced sediment loss by 90%, whereas FS reduced sediment only 60%. The active 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 losses decreased significantly with FS length. Active and dormant switchgrass barriers above FS disperse and temporarily pond concentrated runoff allowing increased sediment deposition and reductions in nonpoint-source pollution while improving the FS performance.