Optimizing nitrogen fertilizer management can reduce nitrous oxide (N₂O) emissions. This study tested if split applying enhanced efficiency fertilizers (EEFs) resulted in lower N₂O emissions than applying equivalent rates of urea at planting. In semiarid southern Alberta, field trials were conducted during three years (planting to harvest) in rainfed winter wheat crops. Annual fertilizer rates ranged from 146 to 176 kg N ha⁻¹. Fertilizer types were urea, and three EEFs (polymer-coated urea, urea with urease and nitrification inhibitors, and urea with a nitrification inhibitor). Each fertilizer type was applied three ways: 100% banded at planting, split applied 30% banded at planting and 70% broadcast in late fall, and split applied 30% banded at planting and 70% broadcast at Feekes growth stage 4 (GS4, post-tiller formation, wheat entering the greening up phase in the early spring). Nitrous oxide was measured using static chambers between sub-weekly and monthly from planting to harvest. Over three years, cumulative N₂O emissions ranged from 0.16 to 1.32 kg N ha⁻¹. This was equivalent to emissions factors between 0.009 and 0.688%. Cumulative N₂O emissions and emissions factors did not differ between fertilizer types, but they were lower when fertilizer was split applied at GS4 compared to in late fall (P ≤ 0.10). Our study suggests that EEFs do not reduce N₂O emissions from rainfed winter wheat crops, but a well-timed split application with a majority of fertilizer applied after winter can minimize N₂O emissions.

优化氮肥管理可以减少一氧化二氮（N ₂ O）排放。这项研究测试了在种植时分批施用增效肥料（EEF）是否导致较低的N ₂ O排放量。在艾伯塔省南部的半干旱地区，对雨养的冬小麦作物进行了三年的田间试验（播种至收获）。年施肥量为146至176 kg N ha ^-1。肥料类型为尿素和三种EEF（聚合物包衣的尿素，具有脲酶和硝化抑制剂的尿素以及具有硝化抑制剂的尿素）。每种肥料类型均通过三种方式施用：播种时100％分条，播种时分30％分条，秋末播种70％分条，播种时分30％分条和Feekes生长第4阶段分条70％分条（GS4，后期） -分formation形成，小麦在早春进入绿化阶段）。从种植到收获，每隔一周至每月使用静态室测量一氧化二氮。在三年中，累积的N ₂ O排放量介于0.16至1.32 kg N ha ^-1之间。这相当于介于0.009和0.688％之间的排放因子。累积氮₂O排放量和排放因素没有肥料类型之间是不同的，但它们是低时肥料是分裂在GS4施加相比，在秋季末（P  ≤0.10）。我们的研究表明，EEF不能减少雨养冬小麦作物的N ₂ O排放量，但是在冬季之后及时施肥并大量施用化肥可以最大程度地减少N ₂ O排放量。