Assessment of Different Quantification Approaches and Application of Multiple

Practices for a Single Farm Unit

Dennis Haak, Agriculture & Agri-Food CanadaOctober 30, 2008.

Outline

1. Methods for Quantifying Soil Carbon

2. Approaches for Quantifying N2O related to Soil Nutrient Management

3. Stacking Multiple Practices on a Single Farm

Methods for Quantifying Soil Carbon

Measurement

Modelling

Methods of Soil Carbon Quantification

Direct Measurement of Soil Carbon

1. Challenges

- low sequestration rates

- high spatial variability

- account for both C concentration and soil bulk density

2. Conclusion

- # of samples required proves cost prohibitive for offset projects

Models for Quantifying Soil Carbon

1. Century 4.0 Model at Ecozone / region scale (5)- GHG inventory reporting from no till, fallow reduction, and conversion of annual crop to perennial forage- no till protocol for GHG carbon offsets

2. Scaling down models to work for smaller regions or possibly individual farms-additional point measurements to validate

Scaling Down Soil Carbon Models

1. C-Lock, Zimmerman, South Dakota- regional scale for historical baseline practices- individual farm for new practices

2. Alberta Specified Gas Emitters Regulation- guidance document for developing model based custom coefficients- criteria: peer reviewed, 3rd party assessment,

validated with long term site data sensitivity and uncertainty analysis

model initialization & multiple runs

Soil Nutrient Management (Focus on N)

1. Principles- optimize source, rate, timing, placement- maximize crop utilization

- minimize environmental losses, including N2O

2. GHG Inventory Process for Soil N2O- driven primarily by rate of N application- spring thaw, landscape position- fallow, irrigation, tillage system

3. No quantification methodology for most practices

Specific Nutrient Management Practices

1. Timing- fall versus spring- single versus split

2. Slow Release Forms of N

3. Increased legumes and pulses in rotation

4. Variable rate nutrient application

5. GPS controlled tracking to eliminate overlap

6. Green manure and cover crops

7. In Field Livestock Winter Grazing and Feeding

Options for N2O Offset Quantification

1. Simplified Approach – based on N rate reduction

- use existing GHG inventory coefficient

- assume N2O reduction leads to N rate reduction

2. Advantages

- easy to monitor and verify

- not necessary to understand N2O mechanism

3. Examples

- N reduction in corn production (SMTWG, 2006)

- Nitrous Oxide Emission Reduction protocol

(Alberta, 2008)

Stacking Multiple Protocols / Practices for One Farm

Rationale

1. Many practices contribute to GHG reductions

2. Benefit for most single practices is small

3. However, cost of adding a practice may be very small

- monitoring and verification already in place

Stacking Multiple Protocols / Practices for One Farm

Process So Far

1. Initial focus on no till – largest GHG benefit

2. Consider other practices that compliment no till

- nutrient management practices

- summerfallow reduction

- increasing frequency of perennial forages in rotation with annual crops

Stacking Multiple Protocols / Practices for One Farm

Challenges

1. Additional GHG reductions must be unique

2. Types of Issues

- practice interactions

- mixed quantification approaches

Practice Interactions

1. Example: No Till and Land Application of Nutrients

2. No Till protocol allows but does not distinguish- nutrient application with low disturbance placement or no incorporation.- timing of application

3. Nutrient Application Protocol- could consider change in timing- could consider low disturbance placement versus no incorporation- could not consider change from high to low disturbance placement without a change in timing

Mixed Quantification Approaches

1. Example: No Till and Fallow Reduction

2. No Till protocol uses regional baseline- discount applied equally to all land regardless of past management

3. Fallow protocol may use individual baseline- easy to verify historical practice of individual land parcels through remote sensing, crop insurance, etc.

4. May be acceptable, but rationalization required

The Potential for Integrated Farm Models

1. Current Examples

- Comet-VR (USDA, Colorado State University)

- Holos (AAFC, NLWIS) (previously GHGFarm)

2. Whole Farm Approach

3. Issue

- original design as an awareness / extension tool needs more work to meet more rigorous requirements of offset system (eg. ISO 14064)

Thank you

Questions and Discussion