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Nitrogen fertilization is essential for optimizing crop yields; however, it increases N 2 O emissions. The study objective was to compare N 2 O emissions resulting from application of commercially available enhanced‐efficiency N fertilizers with emissions from conventional dry granular urea in irrigated cropping systems. Nitrous oxide emissions were monitored from corn ( Zea mays L.) based rotations receiving fertilizer rates of 246 kg N ha −1 when in corn, 56 kg N ha −1 when in dry bean ( Phaseolus vulgaris L.), and 157 kg N ha −1 when in barley ( Hordeum vulgare L. ssp. vulgare ). Cropping systems included conventional‐till continuous corn (CT‐CC), no‐till continuous corn (NT‐CC), no‐till corn–dry bean (NT‐CDb), and no‐till corn–barley (NT‐CB). In the NT‐CC and CT‐CC systems, a controlled‐release, polymer‐coated urea (ESN) and dry granular urea were compared. In the NT‐CDb and NT‐CB rotations, a stabilized urea source (SuperU) was compared with urea. Nitrous oxide fluxes were measured during two growing seasons using static, vented chambers and a gas chromatograph analyzer. Cumulative growing season N 2 O emissions from urea and ESN application were not different under CT‐CC, but ESN reduced N 2 O emissions 49% compared with urea under NT‐CC. Compared with urea, SuperU reduced N 2 O emissions by 27% in dry bean and 54% in corn in the NT‐CDb rotation and by 19% in barley and 51% in corn in the NT‐CB rotation. This work shows that the use of no‐till and enhanced‐efficiency N fertilizers can potentially reduce N 2 O emissions from irrigated systems.
Halvorson et al. (Mon,) studied this question.