PARENT SESSION
Symposium #8: Nitrogen deposition in the Western U.S.... Is there cause for concern?.
Sponsored by ESA Rocky Mountain Chapter
Organized by: H.M. Rueth and J.S. Baron.
Tuesday, August 7, 2001. 8:00 AM to 12:00 PM. Madison Ballroom A

The importance of agricultural nitrogen emissions to western nitrogen deposition.

Baron, Jill¹, Mosier, Arvin ², ^{1 2}

ABSTRACT- Crop and livestock agricultural production systems are important contributors to NH₃ and NO_x emissions. We developed NH₃ and NO_x emission inventories for the State of Colorado and the South Platte River Basin from available records of stationary and mobile sources, confined and pastured livestock, and fertilizer application rates per crop in order to compare the strength of the sources. Regional and statewide estimates can be valuable information to guide NO_x emissions reduction policy, in that they help evaluate whether reductions from mobile and stationary sources alone are sufficient to bring about changes in ecological condition. The South Platte River Basin is a highly productive agricultural region, helping Colorado to rank 4^th in the US for confined/fed cattle production and sheep and lamb production. It ranks 11^th for pig production. Colorado ranks 4^th for winter wheat and 12^th for corn production. Ammonia emissions from livestock (dairy and beef cattle, pigs, poultry, and sheep) are roughly estimated at 11.5 million kg N yr^-1 for 10 counties of the South Platte Basin. Combined irrigated and dryland crops and native rangeland emissions of both NH₃ and NO_x are roughly estimated at 16.0 million kg N yr^-1. NO_x emissions from mobile and stationary sources in this densely populated region are 106.9 million kg N yr^-1. Approximately 20% of the total N emissions of the South Platte Basin therefore come from agricultural emissions.

KEY WORDS: agriculture, emissions, nitrogen, livestock