1. G G reenhouse gas emissions from a commercial corn field Tigist Jima a, Stephen Iwoz a, Dafeng Hui a,Junming Wang b, Sam Dennis a a Tennessee State University b University of Illinois

2. Introduction Approximately 6% of all greenhouse gas (GHG) emissions originating in the United States (U.S.) come from agricultural activities (U.S., EPA, 2010). Approximately 6% of all greenhouse gas (GHG) emissions originating in the United States (U.S.) come from agricultural activities (U.S., EPA, 2010). These gases are in the form of carbon dioxide (CO2), nitrous oxide (N2O), and methane (CH4). These gases are in the form of carbon dioxide (CO2), nitrous oxide (N2O), and methane (CH4).

3. Objectives Using eddy covariance to measure N 2 O fluxes at a commercial farm Using eddy covariance to measure N 2 O fluxes at a commercial farm To compare the EC to chamber- based technologies To compare the EC to chamber- based technologies

4. Eddy Covariance: Emissions of Greenhouse Gases from Commercial Fields N 2 O (0.3-3,000ppb), CO, H 2 O, 10 Hz QCL-TILDAS-76 Ambient Air Monitor Aerodyne Research, Inc

6. Eddy-Covariance Data Processing EddyPro software (Licor Inc.): EddyPro software (Licor Inc.): SAS statistical software SAS statistical software

7. N 2 O Chamber Measurements

8. Preliminary Results Footprint 90% flux contribution distance: 25-95 m 90% flux contribution distance: 25-95 m Field dimension 300 by 500 m Field dimension 300 by 500 m

9. Hourly energy balance (average = -0.5% during 8 am to 6 pm)

10. Diurnal N 2 O and CO 2 concentration

11. Diurnal N 2 O-N and CO2 fluxes

12. N 2 O concentration affected by rainfall

13. Seasonal CO 2 concentration

14. N 2 O-N flux affected by rainfall

15. Seasonal CO 2 flux

16. N 2 O flux vs soil temperature and moisture when Ustar>0.2 m/s during nighttime 4-15 to 4-26 (after 1 st Nitrogen application and before the 1 st large rainfall) 4-15 to 4-26 (after 1 st Nitrogen application and before the 1 st large rainfall)

17. N 2 O flux vs soil temperature and moisture when Ustar>0.2 m/s during daytime (4-15 to 4-26 )

18. N 2 O flux vs soil temperature and moisture when Ustar>0.2 m/s during nighttime (5-5 to 5-25 ) during nighttime (5-5 to 5-25 )

19. N 2 O flux vs soil temperature and moisture when Ustar>0.2 m/s during daytime (5-5 to 5-25 )

20. N 2 O flux vs soil temperature and moisture when Ustar>0.2 m/s during nighttime (6-1 to 6-25) After the 2 nd nitrogen application and the largest rainfall (6-1 to 6-25) After the 2 nd nitrogen application and the largest rainfall

21. N 2 O flux vs soil temperature and moisture when Ustar>0.2 m/s during daytime (6-1 to 6-25) (6-1 to 6-25)

22. Seasonal N 2 O-N total (4-3 to 6-30) 0.26 g/m 2 0.26 g/m 2 2.6 kg/ha 2.6 kg/ha 29 g/ha/day (3.5 kg/ha/120 days) 29 g/ha/day (3.5 kg/ha/120 days)

23. Chamber vs EC measured N2O- N flux

24. Summary Field-scale N 2 O flux measurements using EC are reasonable compared with chamber measurements Field-scale N 2 O flux measurements using EC are reasonable compared with chamber measurements N 2 O-N emission from corn field: N 2 O-N emission from corn field: 29 g/ha/day (3.5 kg/ha/120 days)

25. Acknowledgement Evans-Allen Grant Evans-Allen Grant USDA-CBG Grant USDA-CBG Grant TSU TSU Dr. Roger Sauve Daniel Doss Dr. Sam Dennis Dr. Sam Dennis Dr. Dafeng Hui Dr. Dafeng Hui Dr. Wang Junming Dr. Wang Junming

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