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

Abstract

Abstract Application of 56, 112, or 224 kg N ha −1 as ammonium nitrate (NH 4 NO 3 ) (AN) to barley ( Hordeum vulgare ) plots in northeastern Colorado led to a marked, but short‐lived, increase in nitrous oxide (N 2 O) 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 N 2 O 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 N 2 O 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.