Fertilizer application in crop production agriculture is a major factor influencing soil emissions of the greenhouse gas N 2O. Enhanced efficiency fertilizers (EEFs) have the potential to decrease N 2O emissions by improving the synchrony between soil N supply and crop N demand. This study was conducted to compare the effects of N 2O emissions from soil cropped to corn ( Zea mays L.) and EEFs and conventional fertilizers. During a 3-yr period, growing-season N 2O emissions were quantified in unfertilized check plots and plots fertilized with urea-NH 4NO 3 (UAN), UAN containing the urease and nitrification stabilizer AgrotainPlus (UAN+Ag), a stabilized urea containing urease and nitrification inhibitors (SuperU), and a controlled-release polymer-coated urea (ESN). In the third year of the study, conventional urea and an additional fertilizer formulation, Nutrisphere, were evaluated. We observed no reductions in cumulative seasonal N 2O emissions from treatments fertilized with the EEFs in any of the study years. Generally, N 2O emissions were significantly higher than emissions from the check (no fertilizer) treatment. There were no differences among fertilizer types except in 2009 when the ESN treatment had significantly higher emissions than the check, UAN, and UAN+Ag treatments. Our results indicate that, due to the episodic nature of N 2O emissions induced by rainfall events, reduction of N 2O emissions through the use of EEFs may be limited in rainfed regions.
