Evaluation of Nitrogen Bioavailability Predictors for Poultry Wastes

Long-term land application of manure, litter, and dead-bird compost generated during poultry (Gallus, gallus) production may oversupply nitrogen (N) and result in nitrate (NO3-N) contamination of groundwater. A barrier to judicious use of poultry waste as a fertilizer is the absence of management tools for prediction of waste-derived N released during the plant growing season. This study was conducted to establish an N extraction method for poultry wastes as a predictor of soil N release owing to land application of poultry waste. We correlated N released from 87 different poultry wastes in a 60-day incubation with seven bioavailability predictors. Bioavailability predictors included autoclave-calcium chloride (CaCl2) extraction, bicarbonate extraction, Walkley-Black (acid dichromate) digestion, acid permanganate digestion, pepsin digestion, protein extraction, and barium hydroxide extractable glucose. Results indicate that acid permanganate digestion (r=0.77) has the highest potential for predicting N mineralized from poultry wastes followed by sodium bicarbonate extraction (r=0.51). However, the relationships are not strong enough to indicate that these methods would be useful in a practical, predictive sense.