HR: 0800h
AN: B31A-0064    [Abstracts]
TI: Lime and Soil Moisture Effects on Nitrogen gas Loss Following Fertilizer Application
AU: * Gu, C
EM: cgu@berkeley.edu
AF: Berkeley Water Center, 413 O'Brien hall, Berkeley, CA 94720,
AU: Maggi, F
EM: fmaggi@berkeley.edu
AF: Berkeley Water Center, 413 O'Brien hall, Berkeley, CA 94720,
AU: Riley, W
EM: wjriley@lbl.gov
AF: Earth Science Division, Lawrence Berkeley National Laboratory, 1 cyclotron Rd., Berkeley, CA 94720,
AU: Oldenburg, C
EM: cmoldenburg@lbl.gov
AF: Earth Science Division, Lawrence Berkeley National Laboratory, 1 cyclotron Rd., Berkeley, CA 94720,
AB: The loss of nitrogen from fertilizer application through ammonia volatilization and nitrous oxide emissions are of major environmental concern. Liming has been regarded as a mitigation option for lowering soil nitrogen gas emissions following the addition of fertilizers. A mechanistic nitrogen-cycle model (TOUGHREACT-N) has been developed to simulate the interaction of water saturation variation with biogeochemical processes, and the balance between liming and soil buffering capacity. The model was tested with data from a laboratory soil incubation following the addition of synthetic urine (500 kg N ha-1). Simulation results agreed well with measured N2O emissions and soil inorganic-N concentrations. The study indicated that liming significantly increase NH3 volatilization, while the reduction in cumulative N2O emissions depended strongly on water regime. The cumulative N2O emissions under relatively dry conditions were reduced by up to 243% with liming. However, the cumulative N2O and N2 emissions were predicted to increase by up to 346% following liming because the resulting NO3--N pools (from enhanced nitrification) were susceptible to enhanced N2O and N2 losses during subsequent water application. Consequently, short-term (i.e., days ¡§C weeks) gains made in reducing soil N2O emissions by liming can be offset, and potentially reversed, by emissions later in the growing season. We describe an approach using the modeling framework to optimize N gas reductions using liming under various edaphic, crop type, fertilizer and irrigation application rates, and climate conditions.
DE: 0330 Geochemical cycles (1030)
DE: 0402 Agricultural systems
SC: Biogeosciences [B]
MN: 2007 Fall Meeting