Drainage and N Application Time and Rate Impact Nitrous Oxide Emissions in Poorly Drained Soils in Minnesota.

In poorly drained soils under agriculture, denitrification could be a pathway of loss of N applied to the crops reducing N use efficiency. The objective was to quantify in-season N₂O emissions in corn under tile-drainage and natural (no tile) conditions with different N fertilization management. The study was set up in a split-plot arrangement in a randomized complete-block design with four replications, with drainage as whole plot (drained and undrained) and N treatment as split plot (control, single and split N application). Soil-to-atmosphere N₂O fluxes were measured using the non-steady state chamber method. Results from two year study indicate that drained soils have greater grain yield and grain N removal than undrained soils.  Undrained soils had 1.8 times more cumulative N₂O emissions than drained soils. Nitrogen fertilizer significantly increased emissions 2.1 times for the single- and 1.6 times for the split-application relative to zero-N control treatments. Tile-drainage can reduce N₂O emission from N fertilization. Split-N application can help reduce N₂O emission without negatively impacting corn yield.