Integrated Tillage and Nitrogen Management Effects On Nitrous Oxide Emission Reduction From Cornfields.

About 5.22 million of the estimated 12.6 million tons of nitrogen (N) consumed in the United States in 2008 was used for corn production (USDA-ERS, 2010).  Excessive use of N fertilizers during corn production coupled with low nitrogen use efficiency of corn can result in soil nitrous oxide (N₂O) emissions.  World wide, agricultural N₂O emissions are projected to increase 35-60% by 2030 due to increased N fertilizer use and animal manure production (FAO, 2003). Although, relatively great amount of research has been conducted to determine the effect of various tillage and N management systems on N₂O emissions, results vary widely, and opinion remain divided as to the effects of these management systems.   In particular, limited data exist to assess N₂O emissions following spring sidedress-applied N treated with reformulated nitrapyrin - Instinct™ - especially designed for application with liquid N fertilizers.  On-farm experiments were initiated across Indiana to determine the effect of N fertilizer and “Instinct™” management on seasonal N₂O emission patterns under different tillage practices, determine the effects of a “Instinct™” on N₂O emissions following liquid N fertilizer application and, evaluate the relationship between N application rates and N₂O emission intensity from sidedressed N in cornfields.  Our results indicated that both no-till and the use of the nitrification inhibitor (Instinct™) caused dramatic reductions in N₂O emissions; the magnitude of reduction depended on location.  Nitrous oxide emission was up to 46% less under NT compared to tilled systems.  Depending on soil drainage conditions, addition of Instinct™ to side-dressed UAN fertilizer lowered N₂O emissions by up to 53% in the four counties with on-farm trials. We found that exceeding recommended N fertilizer rates by 30 to 60 pounds N per acre resulted in about 72-100% increase in N₂O emissions.  Soil N₂O emissions were mainly driven by soil temperature and moisture conditions, and addition of the nitrification inhibitor reduced soil mineral nitrogen concentrations for a longer period during the growing season.