Fecal bacteria trapping by grass filter strips during simulated rain

Most fecal wastes produced by the poultry industry in Kentucky will be applied to agricultural land. Grass filter strips have been documented to protect public waterways from soil erosion. We used a rain simulator to investigate their potential to trap fecal bacteria in surface runoff from poultry manure-amended cropland. We incorporated 16.5 Mg ha^-1 of poultry manure into each of four chisel-tilled plots and measured the trapping efficiency of 4.5 and 9.0 m grass filters for runoff sediment and fecal indicator bacteria. Sediment concentrations were reduced an average of 96% by 4.5 m filter strips and 98% by 9.0 m filter strips. Average fecal coliform trapping efficiency was 75% in 4.5 m filter strips and 91% in 9.0 m filter strips. Average fecal streptococci trapping efficiency was 68% in 4.5 m filter strips and 74% in 9.0 m filter strips. Flow-weighted fecal coliform concentrations in filter strip runoff were still 1000 times higher than the standard for primary contact water used in Kentucky (200 fecal coliforms per 100 mL). Grass filter strips long enough to minimize sediment loss will trap most of the fecal bacteria in surface runoff but will not reduce fecal contamination of runoff to sufficiently meet existing water quality standards.