Nitrogen Source Effects On Soil Nitrous Oxide Emissions From Irrigated Corn.

The effect of N fertilizer source on soil nitrous oxide (N₂O) emissions from irrigated continuous corn was evaluated near Fort Collins, CO in 2009 and 2010.  Five N sources (urea, ESN, SuperU, UAN, UAN+AgrotainPlus) were surface band applied at 202 kg N/ha at corn emergence, including a subsurface band application of ESN, and watered (19 mm irrigation water) into the soil the next day.  A check (no N applied) treatment was included.  Nitrous oxide fluxes were measured during the growing season using static, vented chambers for gas sample collection, one to three times per week, and analyzed with a gas chromatograph.  All N sources had significantly lower growing season N₂O emissions than dry granular urea, with UAN+AgrotainPlus having lower N₂O emissions than UAN.  Corn grain yields did not vary with N source, but were higher than the check yield.  Growing season N₂O-N emissions per Mg grain were highest with urea (109 g N/Mg grain) and lowest for UAN+AgrotainPlus (40 g N/Mg grain) under no-till.  In the semi-arid central Great Plains, N source selection is one management practice that can reduce N₂O emissions and help mitigate global climate change.