Simultaneous Measurements of Nitrous Oxide Emissions and Nitrate Loss From Corn Production Under Different Fertilizer and Irrigation Management.

Nitrogen (N) loss from managed systems in the gaseous form as nitrous oxide (N₂O) and the soluble form as nitrate (NO₃^-) is an economic as well as an environmental concern. The objective of this study was to compare N₂O emissions and NO₃^- loss from corn production using various fertilizer N sources combined with different irrigation practices. The experiment was conducted for three consecutive years (2008 – 2010) in central Minnesota in a sandy soil. Nitrogen fertilizer sources evaluated were conventional granular urea (U), polymer coated urea (ESN), and also urea amended with urease and nitrification inhibitors (SuperU, in 2009 and 2010) under rain-fed and irrigated conditions. All fertilizers were applied at rate of 180 kg / ha and a control plot with 0 N was also included. Nitrous oxide emissions were measured using the closed chamber method. Nitrate loss was estimated based on measurement of NO₃^- concentration in soil water collected using ceramic cup lysimeters combined with water-balance estimates of water leaching rates. Nitrous oxide emissions under U and ESN were significantly greater than those from control plots in all three years. Nitrate losses with U, SuperU and ESN were not significantly different from each other whereas N₂O emissions with SuperU was found to be significantly less than those with ESN in 2010. Nitrate losses in leachate were significantly affected by irrigation while irrigation did not have significant effect on N₂O emissions.  These findings suggest that simultaneous measurements of N₂O emissions and NO₃^- loss are important in evaluating N loss pathways from various N sources and irrigation management practices.