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Estimation of in-canopy ammonia sources and sinks in a fertilized Zea mays field
Bash, J. O., J. T. WALKER, JR., G. G. Katul, M. R. Jones, E. Nemitz, AND W. P. Robarge. Estimation of in-canopy ammonia sources and sinks in a fertilized Zea mays field. ENVIRONMENTAL SCIENCE & TECHNOLOGY. American Chemical Society, Washington, DC, 44(5):1683-1689, (2009).
An analytical model was developed that describes the in-canopy vertical distribution of NH3 source and sinks and vertical fluxes in a fertilized agricultural setting using measured in-canopy concentration and wind speed profiles. This model was applied to quantify in-canopy air-surface exchange and above-canopy NH3 flux in a fertilized com (Zea Mays) field. Modeled air-canopy NH3 and sensible heat fluxes agreed well with independent above-canopy flux estimates. Based on the model results at this site, the soil was found to be a consistent source of NH3 one month following fertilizer application, while the vegetation canopy was typically a net NH3 sink with the lower portion of the canopy being a constant sink. On average, the canopy was a sink for 73.2% of the estimated soil NH3 emissions. This suggests that parameterizations of canopy processes in air quality models are necessary to explore the impact of agricultural field level management practices on regional air quality and that there are agronomic and environmental benefits to time liquid fertilizer applications as close to canopy closure as possible