81-9 Field Measurements of Nitrous Oxide Emissions From Two Cotton Sites.

Poster Number 324

See more from this Division: ASA Section: Environmental Quality
See more from this Session: Carbon Sequestration and GHG Emissions From Agricultural & Grassland Systems: Part II.
Monday, October 22, 2012
Duke Energy Convention Center, Exhibit Hall AB, Level 1
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Navreet Kaur Mahal, Plant Science, California State University, Fresno, CA, Dave Goorahoo, 2415 E. San Ramon Ave. M/s AS72, California State University-Fresno, Fresno, CA, Florence Cassel Sharma, 5370 N Chestnut Ave. M/S OF18, California State University-Fresno, Fresno, CA and Bruce Roberts, California State University-Fresno, Fresno, CA
The modeled effects of increasing atmospheric greenhouse gases (GHGs) on potential climate change are being widely debated. Of the three biogenic GHGs (i.e., carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O)), N2O is considered to be the most potent. It has been estimated that in California, agricultural soils accounts for 64% of the total N2O emissions. California’s San Joaquin Valley (SJV) is among the major producers of cotton in the United States. The overall goal of this study was to determine detailed time series measurement of N2O fluxes at crucial management events such irrigation, fertilization, and cultivation, for two cotton sites in the Central Valley of California. The objective for site I was to determine N2O fluxes for cotton fertilized with Urea Ammonium Nitrate (UAN 32) applied with and without a nitrogenase inhibitor. Flux chamber measurements were conducted on beds at four times during the summer. For Site II, the objective was to compare N2O fluxes from cotton furrows and beds fertilized with Urea Ammonium Nitrate (UAN 32). The flux chamber measurements were conducted using an Environmental Protection Agency (EPA) approved methodology to collect air samples (ppm data) which were ultimately analyzed using a Gas Chromatograph (G.C.). Preliminary findings from Site I, indicated that N2O emissions were influenced by N fertilizer rates and irrigation events. For example, field measurements of N2O fluxes ranged from less than 10 to 40 ug N/m2/h for plots receiving 50 to 100lbs N/acre, respectively. After an irrigation event, these fluxes ranged from 20 to 80 ugN/m2/h. More importantly, the nitrogenase inhibitors reduced N2O fluxes by as much as 50%. For Site II, N2O fluxes from beds averaged 128 ugN/m2/d, which was approximately 31% more than that detected from the furrows.
See more from this Division: ASA Section: Environmental Quality
See more from this Session: Carbon Sequestration and GHG Emissions From Agricultural & Grassland Systems: Part II.