Evaluating and Improving Biogeochemical Processes in Canadian Agroecosystems

1. Evaluating and Improving the Parameterization of Biogeochemical Processes Associated with the Flux of N2O from Canadian Agroecosystems Dr. Ray Desjardins Agriculture and Agri-Food Canada Ottawa, Ontario Phone: (613) 759-1522 Fax: (613) 759-1432 Email: Desjardins@em.agr.ca

2. GHG Emissions from Agroecosystems in Canada (in particular N2O) 35 30 25 CO2 20 Tg CO2 equivalent CH4 15 N2O 10 5 0 1981 1986 1991 1996 Year

3. IPCC Methodology 0.304 0.0125 0.696 Crop residue N Grazing Confined 0.02 Excreted livestock N 1.0 0.3 0.0128 Manure N (storage) 0.0125 Biologically fixed N ~1 0.3 0.8 Manure N (non-vol.) Leached N 0.0125 Manure N (applied) 0.025 0.2 Volatilized N 0.1 Fertilizer N 5*10-6 Gg/ha N in Histosols 0.9 Fertilizer N (non-vol.) 0.00693 0.01 0.01 N in sewage Direct emissions Indirect emissions Total emissions

4. Range of Uncertainties for N2O Emissions in Canada

5. Estimated N2O Emissions Using the IPCC Methodology and the Adjusted IPCC Methodology for Canadian Conditions Direct Emissions Indirect Emissions Total from Soils from Animals IPCC Eastern Canada 14.9 6.7 10.9 32.5 Western Canada 41.8 17.7 27.3 86.8 119.3 Adjusted Eastern Canada 14.1 6.2 6.9 27.2 IPCC Western Canada 43.4 14.6 14.9 72.9 100.1

6. A Schematic of the Approach Used to Calculate soil C Change and N2O Emissions

7. DNDC Air temperature/ pcpn Management practices Soil properties Thermal-hydraulic Submodel Plant Submodel Denitrification Submodel Decomposition Submodel • Soil microbial respiration • Hourly N2O • C decomposition • NH3 volatilization • daily root respiration • N utilization • Hourly N2O

8. Our Research with DNDC • Due to the diversity of soil/climatic conditions in Canada it is important to have a tool that can simulate a wide range of conditions. The DNDC model is one such tool that is suitable for such a scenario. We have been working with the model for over 5 years and have corresponded with the author to make improvements to the model when tested versus experimental data. In our experience the pros and cons of the model are as follows: • Pros: • suitable for a wide range of soil/climate conditions • input requirements are easily reached • provides reasonable N2O estimates for many experimental sites • Cons: • Simplistic water flow routine • heat/transfer routine is still in development

9. Predicted seasonal N2O-N emissions for a loam soil in the Gray Brown Luvisol; Barley-Barley-Hay-Hay-Hay rotation in 1990. (Day 135-273: Cumulative 5.50 kg N2O-N ha-1)

10. Estimated direct N2O-N emissions from agriculture soils in Canada for the period between 1970-1999 using DNDC.

11. Comparisons of Measured and Estimated N2O Emissions at the Experimental Site in Ottawa, Ontario (kg N2O-N ha-1 ) Treatment Year Measured DNDC IPCC Control 1993 0.37 0.22 0.91 50t ha-1 stockpiled 1993 0.83 0.73 1.52 Manure 100t ha -1 stockpiled 1993 1.26 1.51 2.06 Manure 200 kg N-NO3- 1994 1.57 1.28 2.23 NH4+ ha-1 Control 1994 0.86 0.59 0.88 100t ha-1 stockpiled 1994 1.48 2.43 1.94 Manure 100t ha-1 composted 1994 0.78 0.56 0.94 Manure

12. Change in Emissions due to Changes in Management (kg N2O-N/ha/y) Control No-till Reduced 150% 50% Fall Add Perm fallow fert fert fert pulse cover Brown Chern. 0.68 -0.23 -0.25 0.17 -0.04 -0.01 -0.10 -0.19 Dark Brown Chern. 1.16 -0.41 -0.3 0.28 -0.08 -0.08 -0.11 -0.37 Black Chern. 1.16 -0.36 -0.09 0.55 -0.21 -0.17 0.04 -0.29 Dark Gray Luv. 1.58 -0.58 -0.21 0.54 -0.18 -0.17 0.40 -0.36 Gray Brown Luv. 2.43 0.36 0.80 -0.65 -0.10 -1.59 Gray Luv. 1.74 -0.06 0.64 0.39 -0.29 0.00 -1.08 Gleysolic 2.87 0.18 0.79 -0.63 0.15 -1.74

13. Carbon Change as a Function of Management Practices Weighted for Crop Rotation, Soil Texture, and Soil Group (Mg C ha-1 yr-1)

14. Expert N Soil temperature profile Soil H2O flow Crop Growth N Transport Dynamic link libraries allow easy interchangeability with other distinct submodels

15. Our Research with Expert-N • Due to the diversity of soil/climatic conditions in Canada it is important to have a tool that can simulate a wide range of conditions. The Expert-N model is one such tool that is suitable for such a scenario. We have been working with the model for over 2 years and have corresponded with the author to make improvements to the model when tested versus experimental data. In our experience the pros and cons of the model are as follows: • Pros: • suitable for a wide range of soil/climate conditions • Interchangeable modules allows great flexibility in simulating very specific sites • Provides good N2O estimates for many experimental sites • Cons: • Can be difficult to meet all input requirements • Model is still in development and is currently not very user-friendly

16. Expert-N vs. Measured (no significant difference between modeled and measured at 95 % CI; r2 = 0.3; units in kg N2O-N/ha/d)

17. Detection Limits of Aircraft-based REA System for Greenhouse Gases N2O (ng N2Om-2s-1) DN2O (ppb) sw = 0.3 m s-1 sw = 0.9 m s-1 0.0125 ng N2O m-2 s-1 Inlet Filter Pump Relief Valve 12 L/min 12 L/min Mass Flow Controller Power Supply Vent 3-Way Valve Vent Pressure Gauge Teflon Bags

18. 13km Satellite image of the study area near Casselman, southeast of Ottawa. The flight track is also shown. 12 km

19. N2O fluxes measured by the Twin Otter aircraft over agricultural fields during the spring of 2001 (N2O tower flux averaged between 11:00-14:00).

20. N2O fluxes measured by the Twin Otter aircraft over agricultural fields during the spring of 2001 and N2O fluxes measured over a corn field fertilized with anhydrous ammonia (N2O tower flux averaged between 11:00-14:00).

21. Summary Aircraft-based flux system • developed to validate N2O emissions on a regional scale. • based on the relaxed eddy accumulation technique. • provides fluxes of N2O with a resolution of about 3 ng N2O m-2 s-1. Results • 0.4 kg N2O-N/ha-1 emissions was measured with the aircraft-based system over two agricultural regions near Ottawa during the spring of 2000. • Estimated N2O emissions from agroecosystems in eastern Canada amounted to about 19 Gg N2O-N in 2001. • Corresponds reasonably well with the 18 Gg N2O-N estimated by DNDC for the period between 1990-1999 and the 17 Gg N2O-N estimated using the IPCC methodology.