During the 1978 growing season, nitrous oxide (N(2)O) emissions from a typical well-managed northern Colorado field of corn (Zea mays L.) totaled approximately 2.6 kilograms of nitrogen per hectare, or about 1.3 percent of the applied fertilizer nitrogen. Thirty percent of the loss occurred during the 3 weeks following fertilization while ammonia was being rapidly nitrified, and 59 percent was emitted during the week after the field's first irrigation, when restricted oxygen diffusion favored denitrification. Considering the large spatial and temporal variability of N(2)O emissions from soil, micrometeorological estimates of vertical N(2)O flux density compared favorably with estimates based on a simple soil cover method.