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Title: Enhanced-efficiency nitrogen fertilizers: potential role in nitrous oxide emission mitigation

Author
item HALVORSON, ARDELL - Retired ARS Employee
item SNYDER, CLIFFORD - International Plant Nutrition Institute (IPNI)
item BLAYLOCK, ALAN - Agrium, Inc
item Del Grosso, Stephen - Steve

Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/26/2013
Publication Date: 6/5/2013
Publication URL: http://doi: 10.2134/agronj2013.0081
Citation: Halvorson, A.D., Snyder, C.S., Blaylock, A.D., Del Grosso, S.J. 2013. Enhanced-efficiency nitrogen fertilizers: potential role in nitrous oxide emission mitigation. Agronomy Journal. Vol. 106:715:722..

Interpretive Summary: Enhanced-efficiency N fertilizers (EENF) have potential for mitigating N2O emissions from N fertilized cropping systems. A synopsis of EENF characteristics is presented. Stabilized EENFs contain nitrification and/or urease inhibitors. Slow-release EENFs contain N components that are slowly released with variable release rates. Controlled-release EENFs release N at predictable rates. A summary of the effectiveness of EENFs in reducing soil N2O emissions from a clay loam soil under irrigated, corn-based production systems in Colorado is presented. A controlled-release, polymer-coated urea, ESN, reduced N2O emissions by 42% compared to urea and 14% compared to UAN (urea-ammonium nitrate solution) in no-till and strip-till environments, but had no effect under conventional plow tillage. A stabilized urea, SuperU, reduced N2O emissions by 46% compared to urea and 21% when compared to UAN. A stabilized UAN source, UAN+AgrotainPlus, reduced N2O emissions by 61% compared to urea and 41% when compared to UAN alone. A slow-release UAN source, UAN+Nfusion, reduced N2O emissions by 57% compared to urea and 28% when compared to UAN. UAN reduced N2O emissions by 35% compared to urea. A linear increase in N2O emissions with increasing N rate was observed for untreated urea and UAN. The N source comparison results presented can be used by developers of N2O mitigation protocols to estimate reductions in N2O emissions from irrigated cropping systems in semi-arid areas when producers use EENF sources. Moreover, these results may be useful for decision and policy makers in determining financial credits needed to encourage producers to use these technologies in their crop production systems.

Technical Abstract: Enhanced-efficiency N fertilizers (EENF) have potential for mitigating N2O emissions from N fertilized cropping systems. A synopsis of EENF characteristics is presented. Stabilized EENFs contain nitrification and/or urease inhibitors. Slow-release EENFs contain N components that are slowly released with variable release rates. Controlled-release EENFs release N at predictable rates. The effectiveness of several EENFs in reducing soil N2O emissions from a clay loam soil under irrigated, corn-based production systems in Colorado (2002-2012) is summarized. A controlled-release, polymer-coated urea (PCU), ESN, reduced N2O emissions by 42% compared to urea and 14% compared to UAN (urea-ammonium nitrate solution) in no-till (NT) and strip-till (ST) environments, but had no effect in a conventional till (CT) environment. A stabilized urea source, SuperU, reduced N2O emissions by 46% compared to urea and 21% when compared to UAN. A stabilized UAN source, UAN+AgrotainPlus, reduced N2O emissions by 61% compared to urea and 41% when compared to UAN alone. A slow-release UAN source, UAN+Nfusion, reduced N2O emissions by 57% compared to urea and 28% when compared to UAN. UAN reduced N2O emissions by 35% compared to urea. A linear increase in N2O emissions with increasing N rate was observed for untreated urea and UAN. Developers of management protocols to reduce N2O emissions from irrigated cropping systems in semi-arid areas can use this information to estimate reductions in N2O emissions when EENFs are used. Policy makers can use this information to help determine financial credits needed to encourage producers to use these technologies in their crop production systems.