Urea Fertilizer Placement Strategies to Reduce Soil Greenhouse Gas Emissions.

Nitrogen (N) fertilization of agricultural soils contributes a significant amount of nitrous oxide into the atmosphere, especially from poorly drained soils. Nitrous oxide is a potent greenhouse gas and has a global warming potential of at least 300 times that of carbon dioxide. Practices to reduce soil nitrous oxide emissions include changing N fertilizer sources and application methods.  The objective of this research was to determine soil surface greenhouse gas emissions from a poorly drained claypan soil grown to corn (Zea mays L.) in Northeastern Missouri utilizing different urea fertilizer placement strategies. These strategies consisted of pre-plant deep banding of urea or urea plus a nitrification inhibitor (NI) at a depth of 20 cm compared to pre-plant urea broadcast surface-applied or incorporated to a depth of 15 cm.  The fertilizer application rate was 180 lb ai/a.  A three-year field trial was initiated in 2014 and greenhouse gas samples were taken frequently throughout the growing season to determine flux and cumulative emissions of nitrous oxide and carbon dioxide, especially after a major rain event.  Results from the first year of this trial will be presented and discussed.