Abstract Peppermint ( Mentha piperita ) is a perennial herb valued for its menthol‐rich oil and requires high nitrogen (N) inputs for its irrigated production. Optimizing N management can reduce nitrous oxide (N 2 O) emissions, a potent greenhouse gas associated with fertilizer N input. A 2‐year experiment (2022–2023) was conducted in western Nebraska to evaluate the effects of N fertilizer sources (urea and polymer‐coated urea; PCU) applied at different rates on peppermint yield and N 2 O emissions. Application rates were lower in 2022 than in 2023 due to transplanting and herbicide injury issues. Therefore, dry matter yield was lower in 2022 (3.38–3.84 Mg ha −1 ) than in 2023 (7.56–14.11 Mg ha −1 ). In 2023, PCU at the highest rate (332 kg N ha −1 ) had a greater peppermint dry matter yield than all other treatment combinations except for urea at the same rate. In 2023, yield did not vary with N source, except at the low rate, where PCU had a greater yield (12.14 Mg ha −1 ) than urea (9.31 Mg ha −1 ). In both years, urea had greater N 2 O emissions than PCU, except for the lowest N rate (34 kg N ha −1 ) in 2022. Nitrous oxide emissions varied by N rates for urea but not for PCU. Fertilizer‐induced emission factors (FIEF) were within the range of the Intergovernmental Panel on Climate Change (IPCC) disaggregated emission factor of 0.5% (0.0%–1.1%) for dry climates. Nitrogen source‐specific FIEF disaggregation might narrow the current IPCC uncertainty range.
Silva et al. (2026) studied this question.