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Combining Urease and Nitrification Inhibitors with Incorporation Reduces Ammonia and Nitrous Oxide Emissions and Increases Corn Yields
- Drury, Craig F., Yang, Xueming, Reynolds, W. Dan, Calder, Wayne, Oloya, Tom O., Woodley, Alex L.
- Journal of environmental quality 2017 v.46 no.5 pp. 939-949
- Zea mays, ammonia, application methods, corn, grain yield, greenhouse gas emissions, nitrification inhibitors, nitrogen, nitrogen fertilizers, nitrous oxide, pollution, soil degradation, urea, urea ammonium nitrate, urease, urease inhibitors, volatilization, weather
- Less than 50% of applied nitrogen (N) fertilizer is typically recovered by corn (Zea mays L.) due to climatic constraints, soil degradation, overapplication, and losses to air and water. Two application methods, two N sources, and two inhibitors were evaluated to reduce N losses and enhance crop uptake. The treatments included broadcast urea (BrUrea), BrUrea with a urease inhibitor (BrUrea+UI), BrUrea with a urease and a nitrification inhibitor (BrUrea+UI+NI), injection of urea ammonium nitrate (InjUAN), and injected with one or both inhibitors (InjUAN+UI, InjUAN+UI+NI), and a control. The BrUrea treatment lost 50% (64.4 kg N ha⁻¹) of the applied N due to ammonia volatilization, but losses were reduced by 64% with BrUrea+UI+NI (23.0 kg N ha⁻¹) and by 60% with InjUAN (26.1 kg N ha⁻¹). Ammonia losses were lower and crop yields were greater in 2014 than 2013 as a result of the more favorable weather when N was applied in 2014. When ammonia volatilization was reduced by adding a urease inhibitor, N₂O emissions were increased by 30 to 31% with BrUrea+UI and InjUAN+UI compared with BrUrea and InjUAN, respectively. Pollution swapping was avoided when both inhibitors were used (BrUrea+UI+NI, InjUAN+UI+NI) as both ammonia volatilization and N₂O emissions were reduced, and corn grain yields increased by 5% with BrUrea+UI+NI and by 7% with InjUAN+UI+NI compared with BrUrea and InjUAN, respectively. The combination of two N management strategies (InjUAN+UI+NI) increased yields by 19% (12.9 t ha⁻¹) compared with BrUrea (10.8 t ha⁻¹).