9420610 Viney Nitric oxide (NO) and nitrogen dioxide (NO2), which together constitute the conserved family NOx, play a key role in the chemistry of the atmosphere, especially in the formation of tropospheric ozone. Natural emissions of these gases from agricultural soils may be comparable in magnitude in rural regions to those from know anthropogenic sources. In particular, the role of nitrogen based fertilizers spread over rural agricultural soils in the production/emission of NOx is not well documented. Rural emissions similar in magnitude to anthropogenic sources make development of effective strategies for reducing ozone concentrations problematic. The objective of this proposal is to participate in an intercomparison study of methodologies for measuring NOx emissions from an intensively managed agricultural row crop. This study is to intercompare chamber and micrometeorological methodologies with extensive onsite characterization of soil physical and chemical properties, ambient air quality and atmospheric conditions.