Nitrogen Fertilizer Management of Temporarily Waterlogged Soils to Improve Corn Production and Reduce Environmental N Loss.

During the 2011 growing season excessive soil moisture in the Unites States accounted for at least 30% of the total crop loss to environmental stresses resulting in more than $3 billion dollars in insurance indemnities paid to farmers. The objectives of this study were to: (i) assess grain yield and N silage uptake for both rescue and non-rescue treatments of different enhanced efficiency products, (ii) determine soil N content among treatments throughout the growing season, and (iii) evaluate PCU release during waterlogging conditions, (iv) quantify soil nitrous oxide emissions among N treatments during soil waterlogging and initially after soils began to dry.  A three-year study of nitrogen (N) loss of enhanced efficiency products during waterlogging durations planted to corn (Zea mays L.) was initiated in 2012 in Northeast Missouri. Fertilizer treatments were urea (NCU), urea plus nitrapyrin (NCU+NI), and polymer coated urea (PCU) (N-Serve^®, Dow AgroSciences) (ESN­^® Agrium, Inc.) applied at 168 kg N ha^-1. Waterlogging durations of 0, 24, and 72 hours were initiated at the V6 growth stage. A rescue N application of 83 kg N ha^-1 of urea plus N-(n-butyl) thiophosphoric triamide (NBPT) was applied at V10 to half of all treatments (Agrotain^®, Koch Agronomic Services).  In the severe drought year of 2012 there were no differences in yield among fertilizer treatments, but a significant grain yield increase did occur from with the rescue N application in the NCU and NCU+NI treated plots after 72 hours of waterlogging. There were no significant increases in the release rate of PCU under waterlogged or no waterlogged conditions. Nitrous oxide emissions were greater with PCU and NCU+NI. This research will be continued through the 2013 and 2014 growing seasons.