Emissions of nitric oxide (NO) were determined from an intensively managed agricultural soil near Plymouth, in the coastal plain of North Carolina, using the dynamic chamber technique. The measurements were made over a soybean field from July 15 to August 15, 1996, as part of the project Natural Emissions of Oxidant Precursors: Validation of Techniques and Assessment (NOVA). A N-containing fertilizer was applied at the middle of the experiment in order to investigate the effect of N-fertilizers on NO emissions and to test the response of instruments. Soil water content was high during the experimental period, with water-filled pore space ranging from 49% to 67%. NO emission during this period ranged between 0.28 and 18.45 ng N m-2 s-1, with an overall average of 5.01¿3.03 ng N m-2 s-1. A normal diurnal pattern with low values at nighttime and high values during the day was observed during the prefertilization period, but a reverse diurnal pattern (high at nighttime, low in daytime) of NO emission variation was found during the postfertilization, closed-canopy period, implying that interaction among canopy development, application of fertilization, and soil parameters may affect the diurnal variation of NO emission from soils. The emissions of NO were related to soil temperature, water-filled pore space, and extractable nitrogen. Application of fertilizer at the middle of the experiment was found to disrupt the normal relations between NO emission and soil temperature and water content seen during the prefertilization period but to enhance the positive relation between NO emission and extractable N. An intercomparison of the dynamic chamber technique with the eddy-correlation technique in this experiment indicates that in spite of large differences in the magnitudes of soil NO emission and the NO flux at 5 m, the two fluxes show similar variations with time and are strongly correlated. ¿ 1999 American Geophysical Union