Exchange of Atmospheric Ammonia in a Mature Corn Canopy

Dry deposition of atmospheric ammonia increases nitrogen levels in terrestrial ecosystems, which contributes to nutrient imbalances and other environmental changes. The exchange of ammonia between the atmosphere and land is dynamic, and vegetative canopies can act as sources or sinks of ammonia under certain conditions. A field study was conducted during summer 2014 in a mature corn field at the University of Illinois using an automated exchange mechanism and a cavity ring-down spectrometer to sample atmospheric ammonia at eight levels between 0.2 m and 4.5 m above the surface. Ammonia concentrations, along with micrometeorological measurements, were evaluated to quantify and characterize ammonia flux profiles to improve understanding of the distribution of ammonia through vegetation.