1 / 17

Margaret Walsh 1 , Steve Del Grosso 2 , and Tom Wirth 3 1 ICF Consulting

Agricultural Soil N 2 O Emissions in the US Greenhouse Gas Inventory: A Comparison of Methodologies. Margaret Walsh 1 , Steve Del Grosso 2 , and Tom Wirth 3 1 ICF Consulting 2 USDA Agricultural Research Service 3 Non-CO 2 Gases and Sequestration Branch, US EPA (Formerly). Overview.

gino
Download Presentation

Margaret Walsh 1 , Steve Del Grosso 2 , and Tom Wirth 3 1 ICF Consulting

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Agricultural Soil N2O Emissions in the US Greenhouse Gas Inventory:A Comparison of Methodologies Margaret Walsh1, Steve Del Grosso2, and Tom Wirth3 1 ICF Consulting 2 USDA Agricultural Research Service 3 Non-CO2 Gases and Sequestration Branch, US EPA (Formerly)

  2. Overview • The US GHG Inventory • Ag N2O • Evolution of Methodologies • IPCC’s Default Method • DAYCENT Simulation • Differences • Inputs • Emission & Partitioning Factors • Conclusions

  3. Inventory of U.S. Greenhouse Gas Emissions and Sinks • Identifies and quantifies the US’s primary anthropogenic GHG sources and sinks • Commitment under the UN Framework Convention on Climate Change • Published annually • Undergoes extensive review process (internal, multi-agency, expert, public, international, UN) • 2005 Review Draft Available Online at: http://yosemite.epa.gov/oar/globalwarming.nsf/content/ResourceCenterPublicationsGHGEmissionsUSEmissionsInventory2005.html • Final available at the same URL on 15 April

  4. 2003 US GHG Inventory Sources Total Gross Emissions: 6,900.2 Tg CO2 Eq. Note: Total does not sum to 100% due to independent rounding.

  5. 2003 Agriculture Sector Emissions Total Emissions: 433.3 Tg CO2 Eq. Note: Total does not sum to 100% due to independent rounding.

  6. In 2005, we’ve moved from a Tier 1 to a Tier 3 Methodology Tier 1: IPCC Default Methods using Nationally Available Data Tier 3: Simulation Modeling, using a Spatially & Temporally Explicit Representations of Biogeochemical Processes

  7. IPCC Method Direct Emissions Indirect Emissions Synthetic N NH3 & NOx Volatilization (10% Synthetic N, 20% Manure N) Manure N NO3- Leaching/Runoff (30%) Mineral Soils Organic Soils 2.5% 1% Temperate: 8 Tg N2O/ha Subtopics: 12 Tg N2O/ha 1.25% Atmospheric N2O

  8. Tier 3 Simulation: DAYCENT • Process • County-Level N Inputs, Soil Info, Climate Data • Daily Timestep • Results • Calculates Volatilization and Leaching Based on Immediate Conditions • Does not Distinguish Organic vs. Mineral Soils • Does not Distinguish N Sources

  9. How do the differences in calculation methodologies lead to different results?

  10. U.S. Cropland Soil N2O Emissions IPCC DAYCENT Average Difference = 14.2%

  11. N Inputs • IPCC: 1.25% EF is applied to all consumed N fertilizer and reported within the Ag Sector, regardless of application. • DAYCENT: Fertilizer application rates are considered by crop and geographic region. 90% of consumed fertilizer is accounted for in this way. • The residual is applied (primarily) to settlement soils, and (secondarily) to forest soils. • Isolated, the net effect would be to reduce emissions.

  12. U.S. Managed Soil N2O Emissions IPCC DAYCENT Average Difference = 11.7%

  13. Emission Factors IPCC EF: 1.25% DAYCENT EF wrt Total Added N Average EF = 0.95%

  14. Nitrate Leaching & Runoff IPCC L&R Factor: 30% DAYCENT L&R Factor wrt Total N Avg = 20.9%

  15. NOx & NH3 Volatilization IPCC Volatilization Factor for Manure N (20%) IPCC Volatilization Factor for Synthetic N (10%) DAYCENT Vol Factor for Synth N(Avg = 2.6%) DAYCENT Vol Factor for Manure N(Avg = 2.0%)

  16. What do these Differences Mean?

  17. In Conclusion • Nationally, Ag Soil N2O is a Key Category. • IPCC Guidelines are being revised now. Revised drivers (indirect fractionation & EFs) should be considered. • For more info: mwalsh@icfconsulting.com

More Related