Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
4758938 | Agricultural and Forest Meteorology | 2017 | 11 Pages |
Abstract
The objective of this research is to quantify NH3 flux above an intensively managed cornfield in the Midwestern United States to improve understanding of NH3 emissions and evaluations of new and existing emission models. A relaxed eddy accumulation (REA) system was deployed above a corn canopy in central Illinois, USA (40°3â²46.209â³N, 88° 11â²46.0212â³W) from May through September 2014 (day of year 115-273) to measure NH3 fluxes due to chemical fertilizer application. NH3 flux was measured in four-hour periods during mornings and afternoons. Mean atmospheric NH3 concentration during the complete measurement period was 2.6 ± 2.0 μg mâ3. Larger upward fluxes of gaseous NH3 were measured during the first 30 days after fertilization, with variations observed throughout the field campaign. Measured NH3 fluxes ranged from â246.0 ng mâ2 sâ1 during wintertime background measurements to 799.6 ng mâ2 sâ1 within two weeks of fertilization (where negative flux indicates deposition). Mean positive flux was 233.3 ± 203.0 ng mâ2 sâ1 in the morning and 260.0 ± 253.3 ng mâ2 sâ1 in the afternoon while mean negative flux was â45.3 ± 38.6 ng mâ2 sâ1 in the morning and â78.35 ± 74.9 ng mâ2 sâ1 in the afternoon. NH3 volatilization during the first 21 days after fertilization accounted for 79% of total nitrogen loss during the growing season. Such measurements are critical to improve understanding of agricultural NH3 emissions in managed agricultural ecosystems dominated by rotations of highly fertilized corn and moderately to lightly fertilized soybeans, such as the plot studied herein. These measurements are also important to improve understanding of how managed agricultural ecosystems impact air quality, and contribute to the global nitrogen cycle, and to evaluate current NH3 emission models.
Keywords
Related Topics
Physical Sciences and Engineering
Earth and Planetary Sciences
Atmospheric Science
Authors
Andrew J. Nelson, Sotiria Koloutsou-Vakakis, Mark J. Rood, LaToya Myles, Christopher Lehmann, Carl Bernacchi, Srinidhi Balasubramanian, Eva Joo, Mark Heuer, Marcelo Vieira-Filho, Jie Lin,