|Rotz, Clarence - Al|
Submitted to: American Society of Agricultural Engineers Meetings Papers
Publication Type: Proceedings
Publication Acceptance Date: 5/15/2005
Publication Date: 7/17/2005
Citation: Rotz, C.A., Oenema, J. 2005. Predicting management effects on ammonia emissions from dairy and beef farms. American Society of Agricultural Engineers Meetings Papers. Paper No. 053054. Interpretive Summary: An interpretive summary is not required.
Technical Abstract: Component models were developed to predict ammonia nitrogen losses from cattle manure in the barn, during storage, following field application, and during grazing. Ammonia loss in each process was predicted using a mechanistic model for ammonia volatilized from the surface of an aqueous solution of ammonium where the ammonia is transported to the free atmosphere through a pathway with a finite resistance. Ammonia emission rate was a function of the ammoniacal content in the manure, ambient temperature, manure pH, manure moisture content, and the exposed manure surface area. Relationships developed for each phase of manure handling were calibrated using published experimental data on ammonia emission rates. This was done by selecting values for the resistance to ammonia transport for the various emission pathways that provided losses similar to those reported. Model relationships were further evaluated to predict long-term average losses similar to those documented in published studies. These relationships were integrated into a whole-farm simulation model to provide a tool for evaluating and comparing long-term nutrient losses along with other performance and economic aspects of farm production. Whole-farm simulations illustrated that the use of a free-stall barn, bottom-loaded slurry storage, and direct injection of manure into the soil reduced ammonia emissions by 30-50% compared to other commonly used animal housing and manure handling systems in the northeastern US. Although injection of manure increased field application costs, the improvement in nitrogen utilization more than offset this cost providing a small increase in farm profitability.