Mitigating Ammonia Deposition Derived from Open-Lot Livestock Facilities into Colorado's Rocky Mountain National Park: State of the Science.

Northeast Colorado's livestock operations have been identified as a major contributor to reactive nitrogen deposition in the Rocky Mountains National Park (RMNP). We present a review on the state of knowledge concerning the emission, transport, deposition, and mitigation of gaseous ammonia (NH₃) from open-lot cattle feeding facilities located east of the Northern Front Range of the Rocky Mountains. Gaseous NH₃ mitigation strategies discussed are related to diet manipulation and management practices. Crude protein content of 11% and condensed tannins of 8% reduced the NH₃ emission by 43% and 57%, respectively. Ambiguous results for NH₃ mitigation by using water sprinklers have been reported—an increase in NH₃ emission by 27% and decrease of 27 to 56%. Manure harvesting should be evaluated in terms of maintaining proper moisture content, and not necessarily as a mitigation option. The use of chemical and physical manure amendments has shown a wide range in NH₃ mitigation effectiveness, ranging from 19 to 98% for chemical and 0 to 43% for physical amendments, respectively. The review outlined the scientific basis, practicality, and expected efficacy of each management practice. The most plausible management practices to reduce NH₃ emissions from corral surfaces in cattle feedyards are presented. [ABSTRACT FROM AUTHOR]