Version 4.0, Build 1

COMET-Planner was updated in September 2025 and includes major changes to emission reduction estimates and the graphical user interface. Please read the methods report for more details on emissions reductions estimates.

  • Graphical User Interface:
  • Major revisions to the user interface update the "look and feel" of the tool while maintaining the general work flow of past versions of COMET-Planner.
  • Users can now view baseline and conservation scenario emissions, in addition to emission changes due to conservation practice adoption.
  • Users can now evaluate more than one county at a time.
  • Emission Reduction Estimates:
  • Most soil emissions estimates were updated in this version to align COMET-Planner with the 2nd Edition of the USDA Methods for Entity-Scale Inventory (Hanson et al. 2024), which includes an updated version of the DayCent model.
  • Woody biomass carbon estimates did not change from the prior version.
  • A number of new conservation practices and practice implementations were added to this version following feedback from stakeholders.

Version 3.1, Build 2

COMET-Planner was updated December 2024 to patch some missing Woody Plantings practices for a few regions. No existing data was altered in this update. Details and methods for biomass carbon in Woody Plantings can be found in the COMET-Planner Report.

Version 3.1, Build 1

COMET-Planner was updated December 2023 and includes major changes to Woody Plantings system types and woody biomass carbon emission reduction estimates. A new estimation method was implemented following guidance in the soon to be released USDA entity-scale quantification methods for agriculture and forestry. The COMET-Planner methods report contains more information and a detailed methods white paper is forthcoming. Estimates for soil carbon and soil N2O have not changed in this update.

Version 3.0, Build 1

COMET-Planner was updated September 2022 and includes major changes to emission reduction estimates and the graphical user interface. Please read the methods report for more details on emissions reductions estimates.


Graphical user interface:

  • Improved site navigation through keyboard navigation and/or assistive technology
  • Improved help documents with accessibility standards in mind
  • Improved text size and contrast colors
  • Alternate text for icons and images
  • Spanish language version

Emission reduction estimates:

  • DayCent 30 cm version: The version of DayCent used in the prior version of COMET-Planner simulated soils to 20 cm depth; the current version simulates soil to 30 cm depth. An overview of differences between versions is summarized here:COMET Versions Comparison – September 2022
  • Irrigation data: Modeled points were classified as irrigated or not irrigated using a new Landsat 30 m based irrigation dataset
  • New practices: New practices were added for adding cover crops (CPS 340) to long-term no-tilled cropland

All estimates derived from COMET-Farm metamodeling utilized COMET-Farm Version 4.0.

Version 2.1, Build 1

COMET-Planner was updated August, 2020 and features a data download option, updates to the user interface, improvements to soil nitrous oxide estimates, and some bug fixes.
  • Data Download: The entire COMET-Planner dataset is now available for download, using the Data Download form.
  • User interface: Info icons have been added to denote place for clickable help/documentation.
  • Soil Nitrous Oxide: Soil nitrous oxide estimates were improved by addition of indirect nitrous oxide emissions from volatilization and leaching. Though direct soil emissions are generally the most dominant source of nitrous oxide emissions, the sum of direct and indirect soil nitrous oxide emissions more accurately represents conservation practice adoption impacts on GHG emission reductions. Contributions of direct and indirect soil nitrous oxide emissions can be viewed in the ‘Detailed Emissions Reductions’ table.
  • Bug fixes: Bug fixes addressed missing counties due to county name mismatches, corrected duplicate grassland practices in a limited region of the midwest, and sample refinements in a limited number of counties in the Great Lakes region.
All estimates derived from COMET-Farm metamodeling utilized COMET-Farm Version 2.0.

Version 2.0

COMET-Planner was updated April 5, 2019 and features a new user interface, refined greenhouse gas estimation methods, and more conservation practice implementation options. A short comparison of versions is given below, but for more information please download theCOMET-Planner report
  • Greenhouse Gas (GHG) Estimation Methods: The first version of COMET-Planner relied on general estimates from meta-analyses and literature reviews. The updated version aligns methods with the USDA entity-scale GHG inventory guidance, using a sample-based, metamodeling approach withCOMET-Farm(COMET-Farm Version 2.0).
  • Spatial Resolution: While users will still select their state and county, like the first version of the tool, the underlying data is now more regionally representative. The updated tool improves spatial resolution of the estimates from sub-national scale broad climate zones to sub-state scale, multi-county regions.
  • NRCS Practice Implementation: The new modeling approaches in the updated tool allowed for more flexibility in defining conservation scenarios, resulting in expanded practice selection. Users can now choose from multiple implementation scenarios for several practices and a number of common practice combinations.

All estimates derived from COMET-Farm metamodeling utilized COMET-Farm Version 2.0.

Version 1.0

The first version of COMET-Planner was released January 2015. Greenhouse gas emission reduction coefficients for COMET-Planner Version 1.0 were derived from meta-analyses and literature reviews and were generalized at the national-scale and differentiated by broad climate zones as defined by the Intergovernmental Panel on Climate Change (IPCC). The first version of COMET-Planner is now retired, however the corresponding report contains all estimates and can be downloaded from the Help page.