An Example of a Tier 3 Inventory Method: Soil Organic C Stock Changes

1. An Example of a Tier 3 Inventory Method:Soil Organic C Stock Changes Lead Compilers: Stephen M. Ogle (Natural Resource Ecology Laboratory, Colorado State University) Keith Paustian (NREL and Dept. of Soil and Crop Sciences, Colorado State University) F. Jay Breidt (Dept. of Statistics, Colorado State University) For more information: US-EPA National GHG Inventory Report, 2008

2. Complexity Accuracy IPCC Method Tiers

3. Does not capture general trends from experimental data? Model Evaluation Unable to locate appropriate input data? Identify Model Inputs Assess Uncertainties Implement Model Model Results deemed unacceptable due to mismatch with evaluation data? Evaluation with Independent Data (Good Practice) Reporting/Documentation Tier 3 Guidance (Adapted from 2006 IPCC Guidelines) Model Selection/Development

4. Climate Soils Management Land Use Change Century Model CO2 CO2 Water Balance Submodel Plant Growth Submodel SOM Submodel Residues CO2 CO2 CO2 CO2 Active SOM Slow SOM Passive SOM CO2 CO2

5. Carbon Sub-Model

6. Tier 3 Guidance (Adapted from 2006 IPCC Guidelines) Model Selection/Development Does not capture general trends from experimental data? Model Evaluation Unable to locate appropriate input data? Identify Model Inputs Assess Uncertainties Implement Model Model Results deemed unacceptable due to mismatch with evaluation data? Evaluation with Independent Data (Good Practice) Reporting/Documentation

7. Century Model Evaluation

8. Tier 3 Guidance (Adapted from 2006 IPCC Guidelines) Model Selection/Development Does not capture general trends from experimental data? Model Evaluation Unable to locate appropriate input data? Identify Model Inputs Assess Uncertainties Implement Model Model Results deemed unacceptable due to mismatch with evaluation data? Evaluation with Independent Data (Good Practice) Reporting/Documentation

9. Johnson County, IA 563 points Note: points not spatially referenced US National Resources Inventory (NRI): Point-Based Survey Data Source: US Dept. of Agriculture

10. Other Key Input Data • Tillage Practices, Conservation Technology Information Center • Mineral Fertilizer Rates, USDA-ERS • Manure amendment application rates by crop type (USDA-NRCS) • Manure available for amendment (US-EPA) • Municipal sewage amendment to agricultural soils (US-EPA)

11. Tier 3 Guidance (Adapted from 2006 IPCC Guidelines) Model Selection/Development Does not capture general trends from experimental data? Model Evaluation Unable to locate appropriate input data? Identify Model Inputs Assess Uncertainties Implement Model Model Results deemed unacceptable due to mismatch with evaluation data? Evaluation with Independent Data (Good Practice) Reporting/Documentation

12. NRI Expansion Factors PDF PDF PDF PDF Uncertainty Framework Input Uncertainty Tillage Practices NRI Survey Sample σ2 Century Model Results Mineral N Fertilization 95% Confidence Interval Manure Amendments Structural Uncertainty

13. Model Input Uncertainty Tillage Practices (CTIC) Johnson County, IA PDF PDF PDF Mineral N Fertilization (USDA-ERS) Manure Amendments (USDA and EPA) Monte Carlo Analysis

14. Uncertainty in NRI Survey NRI Survey is a Two Stage Sample Johnson County, IA NRI Weights NRI survey sample σ2

15. Model Structural Uncertainty • Model algorithms (i.e., equations), parameterization and measurement error • Empirically-Based Approached • Simulate management impacts on SOC storage for experimental sites • ca. 50 sites with over 800 management treatment observations • Linear mixed effect models • Adjust for biases and apply a measure of precision associated with model predictions

16. B A C D Measured Soil C Stock Modeled Soil C Stock Structural Uncertainty: Theoretical Relationships

17. Century Structural Uncertainty Ogle et al. 2007, Ecological Modelling

18. Tier 3 Guidance (Adapted from 2006 IPCC Guidelines) Model Selection/Development Does not capture general trends from experimental data? Model Evaluation Unable to locate appropriate input data? Identify Model Inputs Assess Uncertainties Implement Model Model Results deemed unacceptable due to mismatch with evaluation data? Evaluation with Independent Data (Good Practice) Reporting/Documentation

19. Environmental Conditions Model Inputs Database Management Activity Point Scale Data (NRI Survey) PDF Data Management Results Database Structural Unc. Estimator Run Control Simulation Model: Century Implementation Framework

20. Totals for US Croplands (1990s) Totals for US Croplands (i.e., Major Crops) 2006: -64.0 ± 16% Tg CO2 eq. yr-1

21. Tier 3 Guidance (Adapted from 2006 IPCC Guidelines) Model Selection/Development Does not capture general trends from experimental data? Model Evaluation Unable to locate appropriate input data? Identify Model Inputs Assess Uncertainties Implement Model Model Results deemed unacceptable due to mismatch with evaluation data? Evaluation with Independent Data (Good Practice) Reporting/Documentation

22. Long-Term Monitoring Network(Proposed)

23. Tier 3 Guidance (Adapted from 2006 IPCC Guidelines) Model Selection/Development Does not capture general trends from experimental data? Model Evaluation Unable to locate appropriate input data? Identify Model Inputs Assess Uncertainties Implement Model Model Results deemed unacceptable due to mismatch with evaluation data? Evaluation with Independent Data (Good Practice) Reporting/Documentation

24. Consideration for Reporting Tier 3 Inventory Tier 1 Tier 2 Tier 3 • Tier 3 more complex and can provide more accurate estimates of GHG emissions! • However, National Inventory Report (NIR) must provide transparent explanation of inventory methods, which is a challenge for Tier 3! Complexity Transparency

25. Thanks for your attention!