Nitrous Oxide Emissions in Corn with Different Tillage and N Management Practices.

Agriculture emits to the atmosphere significant quantities of greenhouse gases (GHG’s). More than a third of all N₂O-N emissions are anthropogenic and are primarily due to agriculture. The objectives of this research were to (1) quantify N₂O -N emission under long term (LT) no-till (NT) and till (T) systems and (2) determine the effect of different N placements on N₂O -N emissions in a short-term (ST) (3-years) no-till experiment.   Nitrous oxide emissions were evaluated since summer of 2008 on a Kennebec silt loam. The treatments evaluated in the LTE were NT and T systems with two different types of fertilization (manure (M) and fertilizer (F)).  Three fertilizing placements were evaluated in the ST: Broadcast (BC), Band Superficial (BS), and Band Sub superficial (SB). The results were statistically analyzed using Mixed and Reg procedures from SAS (SAS v 9.1, 2003).   The emissions of N₂O in the LT experiment were not significantly different with regard to till systems and nitrogen source. The inorganic N (NO₃-N and NH₄-N) explained 30% of the variability (p<0.0001) of N₂O-N fluxes. Overall, the average emissions of NT and T were 18.5 and 20.6 g ha^-1 day^-1, respectively. The fertilization treatments F and M were 25.5 and 15.6 g ha^-1 day^-1, respectively. There was an interaction between N management treatments and DOY for the ST experiment. Overall, there were significant differences among the treatments. BS and SB had the highest N₂O-N emissions (109.99 and 90.44 g ha^-1 day^-1, respectively) which were statistically significant from the BC and Control (4.73 and 3.22 g ha^-1 day^-1, respectively). The highest emission during the experiment (768.83 g ha^-1 day^-1) occurred at DOY 201(2008) under BS treatment.