Nitrous Oxide Emissions from Continuous Winter Wheat in the Southern Great Plains

Fertilizer-induced N2O-N emissions (the diff erence between fertilized and unfertilized soils) are estimated to be 0.01 kg N2O-N kg(-1) of applied N. One approach to limiting N2O-N production in soils is by improving nitrogen use effi ciency (NUE) in dryland agricultural systems. However, baseline data on the rate of emissions is needed to determine the potential impact that these eff orts might have on N2O-N concentrations in the atmosphere. A study was established in a long-term continuous winter wheat (Triticum aestivum L.) fertility experiment in Stillwater, OK, to determine the eff ects of N rate on N2O-N emissions from a dryland winter wheatsummer fallow system in the southern Great Plains of the United States to fi ll this knowledge gap. Cumulative emissions of N2O-N varied from year to year and were infl uenced by environment and N rate. Emissions following N fertilizer application were typically highest following N application, as well as toward the end of the summer fallow period, when summer rainfall and temperatures were conducive for N2O-N production chambers within plots historically receiving 134 kg N ha(-1) annually went unfertilized for the 2012-2013 and 2013-2014 crop years and produced N2O-N emissions equivalent to the 45 and 90 kg N ha(-1) rate treatments. Annual cumulative emissions ranged from 0.009 to 0.024 kg N2O-N kg(-1) N applied with an average of 0.015 kg N2O-N kg(-1) N applied, illustrating the variability in N2O-N emissions.