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Rice paddies are one of the major sources of anthropogenic methane (CH₄) emissions. The alternate wetting and drying (AWD) irrigation management has been shown to reduce CH₄emissions and total global warming potential (GWP) (CH₄and nitrous oxide [N₂O]). However, there is limited information about utilizing AWD management to reduce greenhouse gas (GHG) emissions from commercial‐scale continuous rice fields. This study was conducted for five consecutive growing seasons (2015–2019) on a pair of adjacent fields in a commercial farm in Arkansas under long‐term continuous rice rotation irrigated with either continuously flooded (CF) or AWD conditions. The cumulative CH₄emissions in the growing season across the two fields and 5 years ranged from 41 to 123 kg CH₄‐C ha⁻¹for CF and 1 to 73 kg CH₄‐C ha⁻¹for AWD. On average, AWD reduced CH₄emissions by 73% relative to CH₄emissions in CF fields. Compared to N₂O emissions, CH₄emissions dominated the GWP with an average contribution of 91% in both irrigation treatments. There was no significant variation in grain yield (7.3–11.9 Mg ha⁻¹) or growing season N₂O emissions (−0.02 to 0.51 kg N₂O‐N ha⁻¹) between the irrigation treatments. The yield‐scaled GWP was 368 and 173 kg CO₂eq. Mg⁻¹season⁻¹for CF and AWD, respectively, showing the feasibility of AWD on a commercial farm to reduce the total GHG emissions while sustaining grain yield. Seasonal variations of GHG emissions observed within fields showed total GHG emissions were predominantly influenced by weather (precipitation) and crop and irrigation management. The influence of air temperature and floodwater heights on GHG emissions had high degree of variability among years and fields. These findings demonstrate that the use of multiyear GHG emission datasets could better capture variability of GHG emissions associated with rice production and could improve field verification of GHG emission models and scaling factors for commercial rice farms.

Trifluoromethyl‐substituted cyclopropanes (CF₃‐CPAs) constitute an important class of compounds for drug discovery. While several methods have been developed for synthesis oftrans‐CF₃‐CPAs, stereoselective production of correspondingcis‐diastereomers remains a formidable challenge. We report a biocatalyst for diastereo‐ and enantio‐selective synthesis ofcis‐CF₃‐CPAs with activity on a variety of alkenes. We found that an engineered protoglobin fromAeropyrnum pernix(ApePgb) can catalyze this unusual reaction at preparative scale with low‐to‐excellent yield (6–55 %) and enantioselectivity (17–99 % ee), depending on the substrate. Computational studies revealed that the steric environment in the active site of the protoglobin forced iron‐carbenoid and substrates to adopt a pro‐cisnear‐attack conformation. This work demonstrates the capability of enzyme catalysts to tackle challenging chemistry problems and provides a powerful means to expand the structural diversity of CF₃‐CPAs for drug discovery.

Trifluoromethyl‐substituted cyclopropanes (CF₃‐CPAs) constitute an important class of compounds for drug discovery. While several methods have been developed for synthesis oftrans‐CF₃‐CPAs, stereoselective production of correspondingcis‐diastereomers remains a formidable challenge. We report a biocatalyst for diastereo‐ and enantio‐selective synthesis ofcis‐CF₃‐CPAs with activity on a variety of alkenes. We found that an engineered protoglobin fromAeropyrnum pernix(ApePgb) can catalyze this unusual reaction at preparative scale with low‐to‐excellent yield (6–55 %) and enantioselectivity (17–99 % ee), depending on the substrate. Computational studies revealed that the steric environment in the active site of the protoglobin forced iron‐carbenoid and substrates to adopt a pro‐cisnear‐attack conformation. This work demonstrates the capability of enzyme catalysts to tackle challenging chemistry problems and provides a powerful means to expand the structural diversity of CF₃‐CPAs for drug discovery.