NUTRIENT LOSSES IN SURFACE AND SUBSURFACE FLOW FROM PASTURE APPLIED POULTRY LITTER AND COMPOSTED POULTRY LITTER

Over application of poultry litter may cause pollution of surface and ground water. Spatial variability in soil characteristics makes predic tions difficult. Composting poultry litter could reduce the risk of po llution by creating more stable organic components. Three rates of pou ltry litter and compost (10 Mg ha(-1) litter, 20 Mg ha(-1) litter and 10 Mg ha(-1) litter combined with 50 Mg ha(-1) compost) to three water sheds under pasture. The watersheds were monitored for surface and sub surface flow. Nitrate-N concentrations in subsurface flow did not exce ed the U.S. Environmental Protection Agency drinking water standard of 10 mg L-1. Soluble phosphorus concentrations in runoff were high, rea ching a maximum of 8.5 mg L-1 under the compost treatment. These conce ntrations are generally lower than reported on smaller scale studies, which shows the need of studies at the correct scale.