You are here:
MEASUREMENT OF NITROGEN OXIDE EMISSIONS FROM AN AGRICULTURAL SOIL WITH A DYNAMIC CHAMBER SYSTEM
Citation:
Roelle, P. A., V. Aneja, J. O'Connor, W. P. Robarge, D. Kim, AND J. Levine. MEASUREMENT OF NITROGEN OXIDE EMISSIONS FROM AN AGRICULTURAL SOIL WITH A DYNAMIC CHAMBER SYSTEM. JOURNAL OF GEOPHYSICAL RESEARCH: ATMOSPHERES 104(D1):1609-1620, (1999).
Description:
Biogenic soil emissions of nitric oxide (NO) were measured from an intensively managed agricultural row crop (corn, Zea mays) during a 4 week period May 15 through June 9, 1995). The site was located in Washington County, near the town of Plymouth, which is in the Lower Coastal Plain of North Carolina. Soil NO flux was determined using a dynamic flow-through chamber technique. The measurement period was characterized by two distinguishing features: an application of nitrogen (N) fertilizer at the midpoint of the experiment and a nontypical rainfall pattern. Average NO flux prior to the application of N fertilizer was 31.5 +/- 10.1 ng N m-2 s-1 and more than doubled (77.7 +/- 63.7 ng N m-2 s-1) after the application of a side-dressing of N fertilizer. Average soil extractable nitrogen values did not change significantly following application of the side-dressing of N fertilizer. We attribute this failure to detect a significant difference in soil extractable nitrogen following N fertilization to the method in which the fertilizer was applied, the subsequent rainfall pattern, and the technique of soil sampling. NO flux followed the same diurnal trend as soil temperature, with maximum NO emissions coinciding with maximum soil temperature, and minimum NO emissions coinciding with minimum soil temperature. NO flux was found to increase exponentially with soil temperature but only after fertilization. Due to subsurface irrigation practices employed by the farmer, changes in soil water content were minimal, and no relation could be drawn between soil water content and NO flux. Simultaneous measurements of NOy, NO2, and NO emissions revealed that NO and NO2 emissions represent 86 and 8.7%, respectively, of NOy emissions leaving the soil. Simultaneous NO flux measurements made by a closed box flux technique, at the same site, revealed no statistically significant differences between the two different methodologies for measuring NO flux.