Agricultural soils are a significant anthropogenic source of nitrous oxide (N 2 O) to the atmosphere. Despite likely having large emissions of N 2 O, there are no continuous multi-year studies of emissions from poorly drained floodplain soil. In the present study, the micrometeorological flux of N 2 O (F N ) was measured over three years (2006–2008) in a maize (Zea mays L.)/faba (Vicia faba minor L.)/spring-wheat (Triticum aestivum L.) rotation in the Red River Valley, Manitoba, Canada on a gleyed humic verticol soil. Comparison of newly established reduced and intensive tillage treatments showed no difference in F N within the constraints of the high variability between duplicate plots. The annual gap-filled ΣF N across tillage treatments was 5.5, 1.4, and 4.3kgNha −1 in the maize, faba, and spring-wheat crop years, respectively. Emissions from fertilizer N addition and soil thaw the following spring was responsible for the greater ΣF N in the maize and spring-wheat years. Using four approaches to approximate background ΣF N resulted in estimates of 3.5–3.8% and 1.4–1.8% of applied fertilizer N emitted as N 2 O for the maize and spring-wheat crops, respectively. The CO 2 global warming potential equivalent of ΣF N over the three study years was an emission of 5.4MgCO 2 -equiv.ha −1 which adds to the previously determined C balance emission of 11.6MgCO 2 -equiv.ha −1 .