The Uncertainty of Nitrogen Mass Balance for Turkey Housing

Abstract

Quantification of ammonia (NH3) loss from animal feeding operations by measuring gaseous concentration and air exchange through the emitting source is not always practical, e.g., under natural ventilation conditions. Mass balance over an extended period of time may offer a possible remedy. This study compares two NH3-N emission estimate approaches for a commercial turkey grow-out house over one year period: a) a concentration-flowintegration (CFI) method (considered as the reference method), and b) a nitrogen (N) mass-balance (NMB) method. The CFI NH3-N emission was determined by continuously measuring the NH3 concentration and exhaust air flow rate through the turkey house with a state-of-the-art mobile air emission unit. The mass-balance N emission was calculated by balancing the total N inputs (new bedding, young birds, feed) and N output (litter cake removed between flocks, litter removed at cleanout, amount of marketed birds, mortality, and bird body N content), as per records kept by or presented to the cooperative producer. The results revealed a large discrepancy (6273 vs. 2010 kg) in NH3-N loss between the NMB and CFI methods. The outcome of this study cast serious doubt about the adequacy of using mass balance for estimating NH3 emissions from a dynamic production system such as turkey houses.