Atmospheric ammonia (NH₃) is an important precursor of fine particulate matter in the atmosphere, adversely affecting air quality, climate and biodiversity. Ammonia originates mostly from agricultural sources, including N synthetic and organic fertilization. It is important to quantify NH₃ exchange of crops to better understand the conditions favouring ammonia volatilization/deposition in response to fertilizer application and crop growth. However, NH₃ fluxes are challenging to measure because NH₃ is easily adsorbed and desorbed from most surfaces. The study presents the direct eddy covariance (EC) NH₃ fluxes measured over the 2017 and 2018 growing seasons from a urea-fertilized corn field located in Ottawa, Canada. A flux tower was equipped with a 3-D sonic anemometer (CSAT3; Campbell Scientific, UT) and a fast time-response Quantum Cascade Tunable Infrared Differential Absorption Spectrometer (QC-TILDAS; Aerodyne Research, MA) for NH₃ measurements. The second year had a rainfall deficit while the first year had unusual rainfall surplus. During the 2017 growing season, NH₃ emission reached up to 500 ng m^‑2 s^-1 within the first week following urea application as the urea hydrolysis occurred quickly due to significant rain within this period. As the canopy started growing, the NH₃ emissions decreased and at the end of the growing season deposition of NH₃ dominated. In 2018, there was little evidence of NH₃ emission immediately following fertilizer application, but sustained emissions occurred following a rainfall event two weeks later. The results from both years highlight the importance of measuring fluxes over long periods to capture the bi-directional exchanges of NH₃ and evaluate the contribution of NH₃ fluxes to the annual nitrogen budget.