Important terms to understand
Terms
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Field history: The field conditions and management events that occurred on a field before an intervention/practice change.
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Counterfactual baseline: A representation of field management events that would have happened during the time period the intervention took place, if there had been no intervention. This is often considered a hypothetical continuation of pre-intervention practices.
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Cultivation Cycle (also called 'Phase', in legacy versions): A distinct grouping of field management events that correspond to a cultivation cycle. Typically, this is harvest of a commodity crop to the harvest of the following commodity. Cultivation cycles are inclusive of tillage, planting, irrigation, nutrient management and harvest practices, as well as other adopted interventions such as a cover crop in the off season.
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Simulation: A simulation is the process of modeling emissions outcomes on a field using the DNDC model.
- Session name: Is a field along with a collection of field metadata (such as field boundaries), field conditions (such as soil data) and farm management events (such as crop, tillage, irrigation and nutrient management data).
- Reporting information: Time period for which emissions should be quantified.
Intro to Scenarios
A scenario is a data structure defined and used by the API to organize the data needed to run a DNDC simulation. It’s a collection of agricultural field data used to run a DNDC simulation to quantify the emissions impact of the field. For each field that’s submitted to the API, users should provide at least two scenarios for each field, one to represent the historical baseline data and one to represent the practice change data. Then there is an optional counterfactual scenario.
Scenario Types
Historical Baseline
Field history (from before the adoption of an intervention). These are the actual practices that occurred on the field. This scenario is always required to provide data to simulate the history of the field.
Intervention
Intervention are events after the adoption of a practice change. The full cultivation cycle during that practice change should be included.
When used this scenario type leverages the API’s baseline generation functionality (see below).
Coming in v1 (optional) Counterfactual
Allows users to manually define the counterfactual baseline. These are not actual practices that occurred on the field but rather used for comparison. This must be the same length and time period as the intervention scenario and can only be used if baseline method is custom.
Construction of Scenarios
Each SessionInput is composed of:
Scenarios: Scenarios are comprised of weather data, soil data, field location (field boundary) and a rotation (Farm management data).
Rotation: A rotation contains cultivation cycles (phases). A single rotation can contain as many cultivation cycles as needed.
Reporting information: User-defined time period where emissions should be quantified.
Scenario options available
Within Sessioninput there are two allowed combinations of scenario types:
- Historical Baseline + Intervention
- Historical Baseline + Intervention and Counterfactual (coming in v1)
Historical Baseline + Intervention
Historical Baseline + Intervention Scenarios are chosen to take advantage of baseline generation logic within the API.
Baseline autogeneration is only available when the Intervention scenario type is used. In these conditions then the counterfactual baseline is automatically generated for the user by Regrow, and is informed by each field's history.
The user must also choose a methodology for how that baseline counterfactual is generated. Regrow offers a few. Read more on baseline methodologies here.
Historical Baseline + Intervention and Counterfactual (coming in v1)
Historical Baseline and Intervention and Counterfactual are chosen when a client prefers to define their own counterfactual (as opposed to letting the API logic create it(. In this case, the field management events are provided for the historical time period before the intervention/practice change and both the intervention and the counterfactual events are defined by the user to simulate the difference in intervention and business as usual scenarios.
Defining your reporting period
All projects must have reporting information defined. This should contain the full cultivation cycle (usually harvest to harvest) for a field.
- For first year programs, this time will be the same dates as the intervention (example below).
- For multi year programs, this time will be after the practice change has occurred.
