Field to Market’s Soil Carbon Metric uses the SWAT+ model; is this considered a Tier 3 model?

SWAT+ can simulate processes such as soil carbon dynamics, surface runoff, infiltration, evapotranspiration, groundwater flow, sediment transport, and nutrient cycling. When coupled with additional calibration and validation against observed data, it aligns with the IPCC’s definition of a Tier 3 methodology. Tier 3 models are characterized by their comprehensive approaches, disaggregation of activity data, and the use of the latest scientific knowledge to provide granular estimates of variables of interest such as greenhouse gas emissions and removals.

By the end of 2025, Fieldprint Platform V5 will incorporate the SWAT+ model, which Colorado State University will validate to simulate soil organic carbon (SOC) dynamics in the U.S. Corn Belt. This model validation effort focuses on cropping systems that include corn, soybeans, and wheat, among other crops, which collectively comprise 92% of the Field to Market’s project acres. The SWAT+ model implementation by CSU will provide a calibrated model service with localized weather, soil properties, and crop growth modules. Modeling of SOC dynamics for other crops and/or regions outside the Midwest will rely on parameters from the USDA ARS National Agroecosystems Model, built-in parameters, and parameters from the scientific literature. Model uncertainty quantification will be provided for crops and regions with sufficient data.

The model output from SWAT+ should be considered sufficient for Scope 3 reporting.
Generation of carbon credits by SWAT+ is not currently supported.