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<p>Nitrogen (N) fertilizer inputs to agricultural soils are a leading cause of nitrous oxide (<span class="inline-formula">N₂O</span>) emissions. Legume cover crops are an alternative N source that can reduce agricultural <span class="inline-formula">N₂O</span> emissions compared to fertilizer N. However, our understanding of episodic <span class="inline-formula">N₂O</span> flux following cover crop incorporation by tillage is limited and has focused on single-species cover crops. Our study explores whether increasing cover crop functional diversity with a legume–grass mixture can reduce pulse emissions of <span class="inline-formula">N₂O</span> following tillage. In a field experiment, we planted crimson clover (<i>Trifolium incarnatum</i> L.), cereal rye (<i>Secale cereal</i> L.), a clover–rye mixture, and a no-cover control at two field sites with contrasting soil fertility properties in Michigan. We hypothesized that <span class="inline-formula">N₂O</span> flux following tillage of the cover crops would be lower in the mixture and rye compared to the clover treatment because rye litter can decrease N mineralization rates. We measured <span class="inline-formula">N₂O</span> for approximately 2 weeks following tillage to capture the first peak in <span class="inline-formula">N₂O</span> emissions in each site. Across cover crop treatments, the higher-fertility site, CF, had greater cover crop biomass, 2-fold-higher aboveground biomass N, and higher cumulative <span class="inline-formula">N₂O</span> emissions than the lower-fertility site, KBS (<span class="inline-formula">413.4±67.5</span> vs. <span class="inline-formula">230.8±42.5</span> g N<span class="inline-formula">₂</span>O-N ha<span class="inline-formula">⁻¹</span>; <span class="inline-formula"><i>P</i>=0.004</span>). There was a significant treatment effect on daily emissions at both sites. At CF, <span class="inline-formula">N₂O</span> fluxes were higher following clover than the control 6 d after tillage. At KBS, fluxes from the mixture were higher than rye 8 and 11 d after tillage. When controlling for soil fertility differences between sites, clover and mixture led to approximately 2-fold-higher <span class="inline-formula">N₂O</span> emissions compared to rye and fallow treatments. We found partial support for our hypothesis that <span class="inline-formula">N₂O</span> would be lower following incorporation of the mixture than clover. However, treatment patterns differed by site, suggesting that interactions between cover crop functional types and background soil fertility influence <span class="inline-formula">N₂O</span> emissions during cover crop decomposition.</p>