ARS | Publication request: Nitrogen source effects on nitrous oxide emissions from irrigated cropping systems in Colorado. American Chemical Society Symposium Series

Submitted to: American Chemical Society Symposium Series
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 24, 2011
Publication Date: October 11, 2011
Citation: Halvorson, A.D., Del Grosso, S.J. 2011. Nitrogen source effects on nitrous oxide emissions from irrigated cropping systems in Colorado. American Chemical Society Symposium Series. American Chemical Society Symposium Series. 1072:15-27.

Interpretive Summary: Applying nitrogen (N) fertilizers to irrigated cropping systems generally results in increased nitrous oxide (N2O-N) emissions in the semi-arid Central Great Plains. We examined the effects of tillage, cropping system, and commercially available N fertilizer sources on N2O-N emissions from a clay loam soil. Nitrous oxide emissions from urea and a polymer-coated urea were greater in a conventional-till system than a no-till continuous corn system, with the polymer-coated urea significantly reducing N2O-N emissions in the no-till system compared to dry granular urea. Application of a stabilized urea source to no-till corn-barley and corn-dry bean rotations resulted in reduced N2O-N emissions compared to urea. Significant differences in the amount of N2O-N emitted among N sources were found in a no-till continuous corn system. Some enhanced-efficiency N fertilizers reduced N2O-N emissions as much as 50% when compared to dry granular urea and 35% compared to a liquid UAN, fertilizers commonly used by farmers in this semi-arid region. Further work is required to quantify the effectiveness of enhanced-efficiency N fertilizers in reducing N2O-N emissions in other irrigated and non-irrigated systems, on different soil types, and in wetter climates.

Technical Abstract: Nitrogen (N) fertilization is essential in most irrigated cropping systems to optimize crop yields and economic returns. Application of inorganic N fertilizers to these cropping systems generally results in increased nitrous oxide (N2O-N) emissions. Nitrous oxide emissions resulting from the application of commercially available enhanced-efficiency N fertilizers (ESN , Duration III, SuperU, and UAN with AgrotainPlus) were compared with emissions from commonly used urea and urea-ammonium nitrate (UAN) fertilizers under differing tillage (conventional-till and no-till) practices and crop rotations (continuous corn, corn-barley, corn-bean). Significant differences in the amount of N2O-N emitted among N sources were found. Some of the enhanced-efficiency N fertilizers reduced N2O-N emissions as much as 50% when compared to dry granular urea and 35% compared to liquid UAN fertilizers commonly used by farmers in this semi-arid region. Further work is required to quantify the effectiveness of enhanced-efficiency N fertilizers in reducing N2O-N emissions in other irrigated and non-irrigated systems, on different soil types, and in wetter climates.