Fecal bacteria in surface runoff from poultry-manured fields
Animal Waste and the Land-Water Interface , 1995
Coyne, M.S., Blevins, R.L.
Recent growth in Kentucky's poultry industry (from 1.5 million broilers in 1990 to over 43 million broilers in 1993) (Kentucky Agricultural Statistics, 1994) has created an equally large waste disposal problem. As in many states, most of this waste is land-applied without prior processing (Edwards and Daniel, 1992). Manure spreading, while it is a traditional and effective agricultural waste disposal practice, frequently exceeds the rate at which wastes can be processed in agricultural ecosystems. The subsequent runoff of nutrients and fecal bacteria contributes to agricultural nonpoint source pollution and helps to degrade drinking water supplies. Vegetative or grass filter strips are typically established to minimize surface runoff from agricultural fields. They principally reduce sediment runoff (Dillaha et al., 1989). Use of grass filters and grassed waterways to control fecal waste runoff from point sources, such as feedlots, has also been studied (Dickey and Vanderholm, 1981; Schellinger and Clausen, 1992; Young et al., 1980). However, there is little information specifically related to the control of fecal bacteria from agricultural fields treated with poultry manure. Giddens and Barnett (1980) suggested that if runoff water from manured cropland were allowed to flow over grass, its pollution potential would be greatly reduced. However, modeling studies by Walker et al. (1990) implied that buffer strips alone would not be sufficient to bring bacterial concentrations within acceptable limits, for example, below the EPA standard of 200 fecal coliforms/100 mL for primary contact water (bathing and swimming water). Crane et al. (1983) suggested that even after passing through a vegetative filter, runoff contaminated by fecal wastes would have concentrations of fecal indicator bacteria in excess of 103 to 105/100 mL. Because of the growth of the poultry industry in Kentucky, and because information related to grass filter strip use in controlling surface runoff of bacteria from manured fields is limited, we decided to see whether grass filters were an effective management practice to reduce fecal contamination of surface and ground water via runoff from poultry-manured fields. We began a continuing series of rain simulation studies in 1992 to examine this question. This chapter summarizes some of our results.