Holos is a whole-farm model and software program that estimates greenhouse gas (GHG) emissions based on information entered for individual farms. The main purpose of Holos is to test possible ways of reducing GHG emissions from farms and is available at no cost to users.
Users can select scenarios and farm management practices that best describe their operation and then adjust these practices to see the effect on emissions. Examples of these adjustments include changing livestock feed, reducing tillage or including perennial forages in rotation.
Once information is entered into the program, Holos estimates carbon dioxide, nitrous oxide and methane emissions. The sources of emissions include enteric fermentation and manure management, cropping systems and energy use. Carbon storage and loss from lineal tree plantings and changes in land use and management are also estimated. The result is a greenhouse gas emission estimate for the whole farm that can help the user identify ways to reduce farm emissions.
We welcome feedback from researchers, farmers and industry to help us improve this software. For more information on Holos, please contact Holos@agr.gc.ca.
See CONTRIBUTING.md
To see answers to the most frequently asked questions about Holos (both the software and model), visit the FAQ here.
A draft version of the Holos version 4.0 algorithm document is being made available for review
The Holos version 4.0 algorithm document can be found at the following link:
AAFC_Technical_Report_Holos_V4.0_Algorithm_Document_DRAFTVersion_18Nov2024.docx
There is a Holos 4 Training Guide for the graphical user interface (GUI) available. This guide can be used as a step-by-step tutorial on how to set up a farm and calculate emissions in the GUI.
A swine specific training guide can be found here.
A dairy specific training guide can be found here.
A poultry specific training guide can be found here.
Video tutorials on using Holos 4 as well as navigating the GitHub interface can be found here.
There is also a Holos 4 User Guide available. This guide can be used as a more in-depth manual on how to use the various features of Holos.
A complete list of all required and optional inputs required by the model can be found here. An international (non-Canadian) version of this document can be found here.
The GUI for Holos 4 is freely available to download and use from the Agriculture and Agri-Food Canada webpage.
Note that the Holos 4 GUI is not open source at this time.
A command line interface (CLI) version of Holos is available at this link.
Holos version 3 is also available to download. Note that version 3 is no longer supported and is included here for education purpsoses only. Version 3 is provided on an as-is basis only.
Holos v3 - English (Unsupported)
Holos v3 - French (Unsupported)
A table containing information about changes made can be found at Changelog.md.
Unless otherwise noted, the source code of this project is covered under Crown Copyright, Government of Canada, and is distributed under the GNU General Public License (GPLv3).
The Canada wordmark and related graphics associated with this distribution are protected under trademark law and copyright law. No permission is granted to use them outside the parameters of the Government of Canada's corporate identity program. For more information, see Federal identity requirements.