USE OF GRASS FILTER STRIPS TO REDUCE 17-BETA-ESTRADIOL IN RUNOFF FROMFESCUE-APPLIED POULTRY LITTER

Discharge of hormones contained in poultry litter into the environment may disrupt. the health and reproduction of fish and other animals. A runoff study was conducted to evaluate grass filter effectiveness in reducing transport of the estrogen hormone 17 beta-estradiol in runoff from pasture-applied poultry litter. The study objectives were ia det ermine the effects of source (litter-treated) length and grass filter length on runoff concentration and losses of 17 beta-estradiol from po ultry litter applied to tall fescue (Festuca arundinacea Schreber) plo ts. Litter was applied at 5 Mg/ha (2.2 ton/ac) to the upslope 6.1, 12. 2, and 18.3 m (20, 40, and 60 ft) of 24.4-m (80-ft) long grass strips. The corresponding grass filter lengths were 18.3, 12.2, and 6.1 m (60 , 40, and 20 ft), respectively, with the downslope edge of source area s evaluated as a 0-m long filter. Simulated rain was applied at 50 mm/ h (2 in/h) to produce runoff samples for 17 beta-estradiol analysis. R unoff concentrations and mass losses were not significantly affected b y source length and averaged 3.5 mu g/L (ppb) and 1413 mg/ha (0.02 oz/ ac), respectively. Runoff concentrations were reduced by 58, 81, and 3 4% and mass losses by 79, 90, and 98% by filter lengths of 6.1, 12.2, and 18.3 m (20, 40, and 60 ft), respectively. The data from this resea rch indicates that grass fitter. strips can effectively reduce runoff transport of 17 beta-estradiol from tall fescue-applied poultry litter .