Poultry litter and grazing animal waste effects on runoff water quality

In complex landscapes with multiple land uses, it is often difficult to ide ntify the source of contaminant loadings. The objective of this study nas t o compare nutrient runoff as affected by grazing animal depositions vs. pou ltry litter application, Simulated rainfall was applied tn:ire to 1.5 by 6. 0 m runoff plots of tall fescue (Festuca arundinacea Schreb.) with treatmen ts of no waste (CT), dairy calf feces and urine (DFU), poultry litter (PL), and dairy calf feces and urine with poultry litter (DFU + FL). Chemical pr operties of the runoff samples including pH, electrical conductivity (EC), C, soluble reactive phosphorus (SRP), total nitrogen (TN), NH4-N, NO3-N, K, Mg, S, B, Cu, Fe, Mn, Mo, Na, and Zn were determined. Plots receiving poul try litter had significantly greater losses of most nutrient parameters for hath rainfall simulations. For the nutrient parameters of primary interest with regard to water quality, 5.0, 29.5, and 21.9% of the TN, NH4-N, and S RP applied in the PL treatment were transported in runoff during the first rainfall simulation as compared to 3.9. 5.0, and 15.3%, respectively, for t he DFU treatment. Comparable percentages of the applied nutrients were lost from the PL and DFU treatments even though the PL treatment,with the excep tion of NH4-N, provided at least six times the amount of each nutrient. A s evere rainfall er ent shortly after poultry litter application produces sig nificantly greater nutrient lasses as compared to similar application of gr azing animal depositions at the rates used in the experiment.