How do I reflect carbon sequestration in a farming system that uses different tillage for different crops within a rotation?

How do I reflect carbon sequestration in a farming system that uses different tillage for different crops within a rotation?

The IPCC provides definitions for various tillage categories, including "no-till," "reduced," and "full" tillage.  
  1. No-Till: This means that the land used for your crops is never tilled. 
  2. Full Till: This indicates annual or more frequent tillage operations with substantial soil disturbance. It's characterized by minimal residue coverage (<30%) on the surface at planting time. 
  3. Reduced Till: Reduced tillage involves primary and/or secondary tillage but with less soil disturbance, often shallow and without complete soil inversion. Typically, it leaves more than 30% residue coverage on the surface at planting. 
Changes in soil management can have unpredictable effects on soil carbon in the first 3-5 years after a practice change. Therefore, it's advisable to register tillage changes only when you are confident that the transition to a different tillage system will be longer-term (more than 5 years). 

SOC Tier 1 guidance:
  1. When entering tillage changes, consider these terms as applying to the entire rotation on your field, rather than to individual crops within that rotation.If your farming area involves crop management with different tillage practices in rotation, always choose the most conservative/ intensive tillage option for any crop in the rotation. For example, if your management alternates between no-till and reduced till, select "reduced till" for any crop in that rotation.
  2. If the farmer doesn't own the field or is unsure about future tillage plans, assume that the recent tillage system will continue. Assign the most intensive/conservative tillage system used in the cropping rotation during the past 4 years. 
  3. If the field is owned by the farmer, consider adding a question for a Specialist to ask the farmer about their future tillage plans for that specific field. The farmer can select from the existing tillage classes. 
  4. In cases where the farmer plans to apply different tillage options to different crops (e.g., no-till for soy and 1-pass for corn), select the most conservative tillage class for the entire field in the CFT. 
  5. If the farmer is uncertain about their tillage plans, rely on previous data and select the most conservative tillage class that they have historically used. 

SOC Tier 2 guidance:
  1. To more accurately capture the effects of annual management changes, use the Tier 2 SOC model. 
  2. Use the same definitions as listed above, but for each year of your crop rotation you can enter the specific tillage used.