339-7 Annual Nitrous Oxide Emissions in Response to Nitrogen Fertilizer Rates in Lettuce, Tomato, Wheat and Alfalfa Production Systems.

See more from this Division: S11 Soils & Environmental Quality
See more from this Session: Nitrous Oxide Emissions From Agricultural Production Systems
Wednesday, November 3, 2010: 9:35 AM
Long Beach Convention Center, Seaside Ballroom A, Seaside Level
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Martin Burger1, Richard F. Smith2, Tim Hartz3, Johan Six3 and William Horwath1, (1)Dept. of Land, Air and Water Resources, University of California Davis, Davis, CA
(2)University of California Agriculture and Natural Resources, Salinas, CA
(3)Dept. of Plant Sciences, University of California Davis, Davis, CA
Accurate estimates of nitrous oxide (N2O) emissions from N fertilizer applications are needed to develop best management practices that minimize these emissions without decreasing yield potential. Nitrogen fertilizer was applied at five rates ranging from 0 (control) to 340 kg N ha-1 in lettuce, tomato and wheat production systems in California, and N2O flux is being measured by the static chamber technique for two years. In alfalfa, N2O flux is assessed in a first- and a fourth-year stand.  The lettuce crop was sub-surface drip-, tomato was furrow-, and alfalfa was flood-irrigated, whereas wheat was rain-fed. In all treatments in lettuce, during the first year, N2O emissions were <1 kg N ha-1 or <0.3% of the applied N, whereas yields were similar except for the control. In lettuce grower fields, N2O fluxes varied greatly with the highest daily emissions reaching 0.7 kg N ha-1. In tomato, N2O-N in the first year was <1%, and in wheat <0.5% of the applied N. In alfalfa, N2O fluxes were not substantial. Reduction of high N2O emissions may be possible through adjustment of N fertilization rates after accounting for residual inorganic N.
See more from this Division: S11 Soils & Environmental Quality
See more from this Session: Nitrous Oxide Emissions From Agricultural Production Systems