Computer Simulation Model Calibration and Validation for Prediction of Water Quality Impacts of Poultry Waste Disposal

Runoff and water quality data collected from two pairs of grazed fields in northwestern Arkansas were analyzed to support efforts to model runoff quality from areas receiving poultry manure and other fertilizer sources. The monitoring period described in this report was September 1, 1991 to April 30, 1993. One of each pair of fields was fertilized with inorganic fertilizer, and the other received either poultry litter or manure. Losses of fertilizer constituents were quite low from an agronomic standpoint, ranging from approximately 2-11 kg N/ha/year and 0.5-4.1 kg P04-P/ha/year. Annual losses of fertilizer constituents were dominated by only a small number of runoff events. Concentrations and losses of fertilizer constituents were markedly higher for application relatively close to a runoff event than for application well in advance of a runoff event. Runoff fecal coliform concentrations routinely exceeded primary, as well as secondary, contact standards and appeared not to be strongly related to either grazing or poultry litter/manure application