Evaluating N Source and Placement Strategies To Manage N2O Emissions For No-Till Corn.

The global nitrogen (N) fertilizer use in agriculture is projected to increase, in order to improve crop productivity.  Furthermore, agricultural lands that receive N fertilizer are considered as the main source of nitrous oxide (N₂O), a potent greenhouse gas. Strategies that attempt to better match nutrient availability and plant needs, such as N fertilizer source and placement, are recognized as a means to avoid N losses and increase crop nitrogen use efficiency (NUE), but quantification of N₂O emissions is needed. The objective of this study was to evaluate N strategies for N₂O emissions. To test for that, the treatments consisted of a combination between N source and placement: urea broadcasted, UAN broadcasted, coated urea broadcasted, UAN surface-banded, UAN subsurface-banded, UAN + nitrification inhibitor subsurface-banded and a 0 N control. All treatments were applied at a rate of 160 kg N ha^-1 (150 lbs acre^-1). Soil nitrate and ammonium levels are being monitored throughout the growing season. The corn planting and fertilizer application were performed on May 16^th. The N₂O emissions are being monitored using a steady-state vented chamber, once a week before the fertilizer has been applied, two to three times a week right after N application, and once a week thereafter. To date, the treatments with highest cumulative emissions were UAN surface-banded (398 g N-N₂O ha^-1, 0.36 lbs N-N₂O acre^-1) and UAN subsurface-banded (397 g N-N₂O ha^-1, 0.36 lbs N-N₂O acre^-1 ), whereas the ones with the lowest emissions were 0 N (55 g N-N₂O ha^-1, 0.05 lbs N-N₂O acre^-1), coated urea broadcasted (160 g N-N₂O ha^-1, 0.14 lbs N-N₂O acre^-1) and UAN + nitrification inhibitor subsurface-banded (164 g N-N₂O ha^-1 0.15 lbs N-N₂O acre^-1). The experiment is ongoing and future data will be included.