This research assessed fecal bacteria trapping in surface runoff by grass filters and their potential to enhance NO3- removal via denitrification. Grass filter strips 9.0 m long trapped over 99% of the soil in surface runoff in 1992. Fecal coliform removal was less than 75%. In 1993, 9.0 and 4.5 m grass filter strips trapped 99 and 95% of the sediment, respectively. Fecal coliform trapping efficiency was 90% in 9.0 m grass filters and 75% in 4.5 m filters. Fecal streptococci trapping efficiency was 77% in 9.0 m grass filters and only 56% in 4.5 m filters. Fecal coliform concentration in grass filter strip runoff consistently exceeded 200 fecal coliforms per 100 mL. Grass filter strips which minimized sediment loss did not reduce fecal contamination of water to acceptable levels when runoff occurred. Nitrous oxide fluxes were smaller in grass filters than in manured plots. In 1993, N2O loss ranged from 2050 to 11120 mg N2O-N m-2 h-1 in amended soil and 160 to 1060 mg N2O-N m-2 h-1 in grass filter strips. Denitrification was not apparently enhanced in the grass filters relative to the manured soil.
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The work upon which this report is based was supported in part by funds provided by the United States Department of the Interior, Washington, D.C. as authorized by the Water Resources Research Act of P.L. 101-397.
Additional support was provided by funds allocated by Kentucky State Senate Bill 271.
Coyne, Mark S.; Blevins, Robert L.; and Gilfillen, Rebecca A., "Use of Riparian Vegetated Filter Strips to Reduce Nitrate and Fecal Contamination in Surface Water" (1994). KWRRI Research Reports. 20.