Nitrous Oxide Emissions from Barley Plots Treated with Ammonium Nitrate or Sewage Sludge

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Abstract
Application of 56, 112, or 224 kg N ha−1 as ammonium nitrate (NH4NO3) (AN) to barley (Hordeum vulgare) plots in northeastern Colorado led to a marked, but short‐lived, increase in nitrous oxide (N2O) emissions that was linearly related to the amount of AN applied. The AN treatment effects became statistically insignificant after about 6 weeks. Compared with total N2O emissions of 0.54 kg N ha−1 from the control plots, totals from the AN‐treated plots ranged from 0.93 to 1.43 kg N ha−1, representing an average 0.5% of the fertilizer added. Nitrous oxide emissions from plots treated with 16.7 metric tons ha−1 dry anaerobically digested sewage sludge (SS) totaled 1.09 kg N ha−1 and exhibited temporal variability similar to that of AN‐treated plots, while the emissions from plots treated with 83.5 metric tons SS ha−1 were significantly larger than from the other treatments throughout the 155‐day study period and totaled 4.19 kg N ha−1. The increase in N2O emissions that results from application of organic or inorganic N amendments appears to be much smaller than assumed by models developed to describe the effect of agricultural fertilizers upon stratospheric ozone depletion.