Nitrogen released from poultry litter
Mowrer, Jason Erik
MetadataShow full item record
Poultry waste in the form of broiler litter (BL) has intrinsic value to crop producers for its phosphorus (P), potassium (K), and nitrogen (N) content. This dissertation research is focused on the N content. It improves a method for analyzing uric acid N from poultry waste. Use of 0.1 M sodium acetate to extract the waste, separation by HPLC, and detection by UV/VIS at 290 nm resulted in substantially improved recoveries ranging from 88.7 to 109.1% (n = 22; mean = 100.1%, median = 98.8, and σ = 4.8). Stability of the analyte in extraction solution was improved to > 2 days. Near infrared reflectance (NIR) spectroscopy was used to develop rapid analysis methods for the prediction of important forms of N in BL samples. Calibrations were developed for total-N (r2 = 0.896), NH4-N (r2 = 0.795), NO3-N (r2 = 0.926), uric acid-N (UAN) (r2 = 0.909), organic-N (ON) (r2 = 0.821), water soluble organic-N (WSON) (r2 = 0.897), potentially mineralizable-N (PMN) (r2 = 0.842), and initial plant available (PAN + PMN) (r2 = 0.888). Incubation experiments for PMN used to calibrate the NIR instrument suggested that stored poultry wastes release less PAN (mean = 33%) than those collected fresh from poultry houses (mean = 50-60%). Changes in UAN and xanthine-N (XN) in BL showed early increases in concentration followed by declines over the course of 38 days. A strong relationship was found between the first-order decay-rate constants for these compounds and water potential (ψ) in the BL samples: kUAN = 0.0054(ψ) + 0.101 (r2 = 0.9987); and kXN = 0.0066(ψ) + 0.1101 (r2 = 0.9285).