Broadcast Urea Reduces N2O but Increases NO Emissions Compared with Conventional and Shallow-Applied Anhydrous Ammonia in a Coarse-Textured Soil
- Ryosuke Fujinumaa,
- Rodney T. Venterea *ab and
- Carl Rosenb
- a USDA–ARS, Soil & Water Management Research Unit, St. Paul, MN 55112; R.T. Venterea and
b Dep. of Soil, Water, & Climate, Univ. of Minnesota, St. Paul, MN 55112. Mention of trade names or commercial products in this publication is solely for the purpose of providing specific information and does not imply recommendation or endorsement by the U.S. Department of Agriculture. Assigned to Associate Editor Martin H. Chantigny
Despite the importance of anhydrous ammonia (AA) and urea as nitrogen (N) fertilizer sources in the United States, there have been few direct comparisons of their effects on soil nitrous oxide (N2O) and nitric oxide (NO) emissions. We compared N oxide emissions, yields, and N fertilizer recovery efficiency (NFRE) in a corn (Zea mays L.) production system that used three different fertilizer practices: urea that was broadcast and incorporated (BU) and AA that was injected at a conventional depth (0.20 m) (AAc) and at a shallower depth (0.10 m) (AAs). Averaged over 2 yr in an irrigated loamy sand in Minnesota, growing season N2O emissions increased in the order BU < AAc < AAs. In contrast, NO emissions were greater with BU than with AAc or AAs. Emissions of N2O ranged from 0.5 to 1.4 kg N ha−1 (50–140 g N Mg−1 grain), while NO emissions ranged from 0.2 to 0.7 kg N ha−1 (20–70 g N Mg−1 grain). Emissions of total N oxides (NO + N2O) increased in the order AAc < BU < AAs. Despite having the greatest emissions of N2O and total N oxides, the AAs treatment had greater NFRE compared with the AAc treatment. These results provide additional evidence that AA emits more N2O, but less NO, than broadcast urea and show that practices to reduce N2O emissions do not always improve N use efficiency.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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