Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 13, 2013
Publication Date: N/A
Interpretive Summary: Nitrogen fertilizer use in row crop agriculture has a major impact on soil emissions of the greenhouse gas, nitrous oxide. Better fertilizer management practices are needed to increase crop yields while at the same time reducing adverse environmental effects such as greenhouse gas emission. The use of 'smart' fertilizers that slowly release nitrogen when the crop needs it or that inhibit the soil bacterial processes that produce nitrous oxide have shown promise in promoting yield and reducing environmental impacts. This study evaluated the effects of several different types of fertilizers on soil nitrous oxide emissions from a corn production system in central Iowa. We observed that major peaks of nitrous oxide emissions occurred after rainfall events. Over this three-year study we found no significant reductions in total nitrous oxide emissions through the use of smart fertilizers as compared to conventional fertilizers. We conclude that control of nitrous oxide emissions through the use of smart fertilizers may be of limited value in rain-fed regions of the country. This information will be useful to other scientists in designing nitrogen management strategies and to regulatory agencies charged with documenting environmental effects of agriculture.
Technical Abstract: Fertilizer application in crop production agriculture is as a major factor influencing soil emissions of the greenhouse gas N2O. Enhanced efficiency fertilizers (EEFs) have the potential to decrease N2O emissions by improving the synchrony between soil N supply and crop N demand. This study was done to compare the effects of soil N2O emissions from soil cropped to corn and EEFs and conventional fertilizers in. Over a two-year period growing season N2O emissions were quantified in unfertilized check plots and plots fertilized with UAN, UAN containing the urease and nitrification stabilizer AgrotainPlus (UAN+Ag), a stabilized urea containing urease and nitrification inhibitors (SuperU), and a slow 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 N2O emissions from treatments fertilized with the EEFs in any of the study years. Generally, N2O 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 N2O emissions induced by rainfall events, reduction of N2O emission through the use of EEFs may be limited in rain-fed regions.