Title: Estimation of ammmonia emissions from beef cattle feedyards in the Southern Plains with process-based modeling Authors
Submitted to: ASA-CSSA-SSSA Annual Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: July 19, 2012
Publication Date: N/A
Technical Abstract: Ammonia (NH3) emissions from beef cattle feedyards represent a loss of N that could be useful for crop production and this loss has negative environmental consequences. Models have been developed to estimate NH3 emissions from various livestock production systems; however, little work has been conducted to assess their accuracy for large open-lot feedyards. The objectives of this study were to investigate the ability of two process-based models, Manure DNDC and the Integrated Farm System Model (IFSM), to predict daily NH3 flux from feedyards in the Southern High Plains. To evaluate the models, simulated NH3 flux was compared to emissions data collected from two commercial feedyards in Texas. Model predictions by Manure DNDC were in good agreement with measured observations from both feedyards, and reflected high sensitivity to variations in air temperature and dietary crude protein level. Predicted mean daily NH3 flux densities for the two feedyards were 43.6 and 55.7 kg NH3-N ha**1 d**1, and were not significantly different from observed data (p < 0.001). This indicates that Manure-DNDC can assist with NH3 emissions reporting for commercial feedyards, and can be used to evaluate the effects of management practices on N loss. Evaluation of IFSM will be conducted in June 2012.