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ARS Home » Midwest Area » Columbia, Missouri » Cropping Systems and Water Quality Research » Research » Publications at this Location » Publication #154368
Title: GRASS BARRIER AND VEGETATIVE FILTER STRIP EFFECTIVENESS IN REDUCING RUNOFF, SEDIMENT, NITROGEN AND PHOSPHORUS LOSS

Author
item BLANCO-CANQUI, HUMBERTO - UNIV OF MO
item GANTZER, C - UNIV OF MO
item ANDERSON, S - UNIV OF MO
item Alberts, Edward
item THOMPSON, A - UNIV OF MO

Submitted to: Soil Science Society of America Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/5/2004
Publication Date: 9/1/2004
Citation: Blanco-Canqui, H., Gantzer, C.J., Anderson, S.H., Alberts, E.E., Thompson, A.L. 2004. Grass barrier and vegetative filter strip effectiveness in reducing runoff, sediment, nitrogen and phosphorus loss. Soil Science Society of America Journal. 68:1670-1678.

Interpretive Summary: Sediment, nitrogen (N), and phosphorus (P) can move in runoff from agricultural cropland degrading downstream surface water supplies. To reduce such nonpoint-source (NPS) pollutants, various field practices have been used. One practice commonly used is to plant riparian zones between streams and croplands. A commonly used practice is a grass filter strip planted to fescue. Fescue is a short, sod-forming grass that requires little management. The use of narrow, stiff-stem grass barriers is a new alternative that may be as or more effective in reducing NPS pollution in addition to improving species diversity and wildlife habitat. The objective of this study was to compare several alternative grass barriers/filter-strip designs to a standard fescue filter strip. One alternative evaluated was to plant a narrow switchgrass barrier above a fescue filter strip for additional sediment and nutrient trapping. Another alternative was to plant a switchgrass barrier above a mixture of native plant species that provide taller, more diverse vegetation for better wildlife habitat. Native species used included eastern gamagrass, Indian grass, big bluestem, gray-head coneflower, and purple coneflower. Treatments were evaluated by applying rainfall with a rotating boom rainfall simulator at a rainfall intensity of 66 mm/h. Plots were 1.5-m wide by 16-m long. The upper half of each plot was maintained in continuous cultivated fallow to generate the maximum amount of soil erosion and nutrients entering the barriers and vegetative filter strips. Samples were collected at the downslope end of the fallow area and at 0.7-, 4-, and 8-m lengths within each filter strip. Switchgrass barriers in combination with fescue or native vegetative filter strips retarded runoff and reduced sediment, N, and P losses more than the fescue filter strip alone. The filter strip comprised of native species coupled with the narrow switchgrass barrier caused the highest reduction in runoff, sediment, N, and P. Another finding was that most of the reduction in runoff, sediment, N, and P occurred within a 4-m length of the vegetative filter strip 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: Grass barriers show potential as an economical conservation practice. This study evaluates the effectiveness of switchgrass (Panicum virgatum) barriers, traditional fescue(Festuca arundinacea) filter strips (fescue-FS), and native species filter strips with barriers (native-FS-B) for reducing runoff, sediment, nitrogen (N), and phosphorous (P)losses from 1.5- by 16-m plots on a Mexico silt loam (Vertic Aeric Epiaqualfs). Grass barriers (0.7-m long) were established below 1.5- by 8-m long plots(sediment source areas)under continuous cultivated fallow and above 1.5- by 8-m long filter strips(FS). Runoff produced from simulated rainfall at 66 mm/h was sampled at 1 m above the downslope edge of the sediment source area, and 0.7, 4, and 8 m below the source area to measure sediment, N, and P concentrations with distance. Barriers and fescue-FS of equal length (0.7 m) significantly reduced runoff and sediment loss, but barriers reduced runoff 31% more(P<0.05) and sediment 15% more(P<0.01)than fescue-FS. Barriers also reduced organic N, NO3-N, NH4-N, particulate P, and PO4-P more than fescue-FS (P<0.01). Native-FS-B when used with barriers reduced runoff 30% more than fescue-FS and were equally effective for reducing sediment and nutrient losses. Effectiveness of the FS increased with distance, but ~25% of runoff, ~94% of sediment, and ~78% of the nutrient losses were reduced in the first 4 m of FS. A modified equation accounting for runoff ponding above barriers explained >70% of the variability between measured and predicted values of sediment, organic N, and particulate P transport. Barriers and native-FS-B show promise for reducing sediment and nutrient losses in runoff and can be alternatives to fescue-FS while promoting wildlife habitat.