Holos

The Holos model is a software application that estimates greenhouse gas (GHG) emissions and changes in soil carbon (C) in Canadian farming systems. The model’s development focusses on enhancing the environmental sustainability of Canadian farming by testing, validating, and providing sustainability attributes for Canadian agricultural production systems.

Based on information entered for individual farms, the main purpose of Holos is to test possible ways of reducing GHG emissions and increasing soil C stocks by exploring the effects of different management practices. 

In the Holos model interface, users can ‘build’ their model farm using the available cropping, livestock, and machinery components, and then create scenarios that best describe their operation. Model settings and management practices can be adjusted to examine the effect on GHG emissions and soil C. Examples of these adjustments include changing livestock diets, reducing tillage or including perennial forages in a rotation.

Once information is entered into the program, Holos estimates net emissions of carbon dioxide (CO2), nitrous oxide (N2O), and methane (CH4), in carbon dioxide equivalents, calculated for the various farm components. The sources of emissions include enteric fermentation and manure management, cropping systems and energy use. Carbon storage and loss from fields used for grazing and crop production and lineal tree plantings and are also estimated in response to changes in land use and management. The model includes 36 commonly grown annual and perennial crops, summer fallow, native rangeland, tame pasture and 8 types of tree plantings, along with beef, dairy, sheep, swine, poultry and other livestock operations. The model relies on extensive climate, soil, and agronomic databases to populate regionally-applicable default values. The result is a GHG and soil C estimate for the whole farm that can help the user identify ways to reduce farm emissions.

Holos is continually being updated with new data and improved features and is available at no cost to users. The most current version of Holos is version 4.0, available in both English and French.

Holos 4.0 Installation Package

We welcome feedback from researchers, farmers, and industry to help us improve this software. The team is preparing the model for collaborative development (now open source) and is thus looking for opportunities to involve the expertise of other groups outside of AAFC to facilitate their inclusion in future versions.

User documentation and a frequently asked questions (FAQ) page is available on the Holos GitHub website.

For more information on Holos, please contact holos@agr.gc.ca.

Related publications

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• Judson Christopherson, J., and Smyth, S.J. 2025. Assessing Saskatchewan forage production with regard to carbon and nitrogen emissions. Agricultural Systems. Vol 228:104391.
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• Sheikh, S., and Khalil, M. I. 2025. Automating Spatial Data Integration for HOLOS-IE: Irish Case Study with Soil and Land Cover. Preprints.
• Aboagye, I.A., Valappil, G., Dutta, B., Imbeault-Tétreault, H., Ominski, K.H., Cordeiro, M.R.C., Kröbel, R., Pogue, S.J., and McAllister, T.A. 2024. An assessment of the environmental sustainability of beef production in Canada. Canadian Journal of Animal Science . 104(2):221-240.
• Åby, B.A., Samsonstuen, S., Beauchemin, K.A., and Aass, L. 2024. Modelling of on-farm greenhouse gas emissions from dual-purpose meat and wool sheep production in different geographical regions of Norway. Livestock Science. Vol 283:105472.
• Bamber, N., Arulnathan, V., Puddu, L., Smart, A., Ferdous, J., and Pelletier, N. 2024. Life cycle inventory and assessment of Canadian faba bean and dry bean production. Sustainable Production and Consumption. Vol 46: 442-459.
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• Boonstra, E., Aboagye, I.A., McAllister, T.A., Legesse, G., Mengistu, G.F., Fulawka, D.L., Cordeiro, M.R.C., Ribeiro, G.O., McGeough, E., and Ominski, K.H. 2023. Modelling environmental impacts associated with the removal of productivity-enhancing technologies from Canadian feedlots: a case study. Canadian Journal of Animal Science . 103(3):249-261.
• Kroebel, R., Pogue, S., McPherson, A., and Mantle, P. 2023. 403-9 - The Holos Model - the Canadian National Greenhouse Gas Inventory Downloaded to the Farm Level to Aid Decision Making. [Abstract]. ASA, CSSA, SSSA International Annual Meeting, Oct 29-Nov 1, 2023. St. Louis, MO. (Presentation)
• Niloofar, P., Lazarova-Molnar, S., Thumba, D.A., and Shahin, K.I. 2023. A conceptual framework for holistic assessment of decision support systems for sustainable livestock farming. Ecological Indicators. Vol 155:111029.
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• Fouli, Y., Hurlbert, M., and Kröbel, R. 2021. Greenhouse Gas Emissions From Canadian Agriculture: Estimates and Measurements. SSRN. SPP Briefing Paper. Vol 14:35.
• Holtshausen, L., Benchaar, C., Kröbel, R., and Beauchemin, K. A. 2021. Canola Meal versus Soybean Meal as Protein Supplements in the Diets of Lactating Dairy Cows Affects the Greenhouse Gas Intensity of Milk. Animals 11(6):1636.
• Kröbel, R., Alemu, A., Pogue, S. and McPherson, A. 2021. 169 Estimating the Environmental Impact of Livestock Operations Using the Canadian Whole-farm Model Holos Developed for Canadian Farmers. Journal of Animal Science 99:90-90.
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• Kröbel, R., Moore J., Ni, Y. Z., McPherson A., Poppy L., Soolanayakanahally R. Y., Amichev B. Y., Ward T., Laroque C. P., Van Rees K. C. J., and Akhter F. 2020. Demonstration and Testing of the Improved Shelterbelt Component in the Holos Model. Frontiers in Environmental Science. 8:149.
• Kroebel, R. Alemu, A.W. McPherson, A. and Pogue, S. 2020. The Canadian whole-farm model Holos - development of the new Version 4. American Geophysical Union. Abstract #GC099-0007. Fall Meeting 2020. (Presentation)
• Alvarez-Hess, P.S., Little, S.M., Moate, P.J., L. Jacobs, J.L., Beauchemin, K.A., and Eckard, R. J. 2019. A partial life cycle assessment of the greenhouse gas mitigation potential of feeding 3-nitrooxypropanol and nitrate to cattle. Agricultural Systems 169:14-23.
• Buckingham, S., Crooks, B., Dolan, S., Dragosits, U.H., Eory, V., Rees, R., and Topp, K. 2019. Comparative analysis of nitrogen accounting models with particular reference to agriculture. ClimateXChange: Scotland.
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• Mayrinck, R. C., Laroque, C. P., Amichev, B. Y., and Van Rees, K. 2019. Above- and Below-Ground Carbon Sequestration in Shelterbelt Trees in Canada: A Review. Forests. 10(10):922.
• Mirmasoudi, S., Byrne, J., Kroebel, R., Johnson, D., and MacDonald, R. 2019. Modelling historical and potential future climate impacts on Keremeos Creek, an Okanagan-Similkameen watershed, British Columbia, Canada: Part II. Forecasting change in farm-level greenhouse gas emissions. Canadian Water Resources Journal / Revue Canadienne Des Ressources Hydriques, 44(4):367–381.
• Guest, G., Smith, W., Grant, B., McConkey, B., Chipanshi, A., Reid, K., Kroebel, R., Martel, M., Desjardins, R., VanderZaag, A., Pattey, E., Glenn, A., Wilson, H., Balde, H., Wagner-Riddle, C., Drury, C. F., Fuller, K., Hayashi, M., and Reynolds, D. 2018. Comparing the performance of the DNDC, Holos, and VSMB models for predicting the water partitioning of various crops and sites across Canada. Canadian Journal of Soil Science. 98(2):212-231.
• Gülzari, S.O., Ahmadi, B.V., and Stott, A.W. 2018. Impact of subclinical mastitis on greenhouse gas emissions intensity and profitability of dairy cows in Norway. Preventive Veterinary Medicine. 150:9-29.
• Little, S., Benchaar, C., Janzen, H., Kröbel, R., McGeough, E., McPherson, A., and Beauchemin, K. 2018. Using whole-farm analysis based on Holos to reduce net greenhouse gas emissions: examples from dairy systems. American Dairy Science Association Annual Meeting, Knoxville, Tennessee, USA, June 24-27, 2018. (Presentation)
• Possberg, M., and Kulshreshtha, S. 2018. Beef enterprise profitability and greenhouse gas emissions on Manitoba farms. EC Agriculture. 4.1:29-38.
• Rotz, C.A. 2018. Modeling greenhouse gas emissions from dairy farms. Journal of Dairy Science. Vol 101(7):6675-6690.
• Alemu, A. W., Janzen, H., Little, S., Hao, X., Thompson, D. J., Baron, V., Iwaasa, A., Beauchemin, K. A. and Kröbel, R. 2017. Assessment of grazing management on farm greenhouse gas intensity of beef production systems in the Canadian Prairies using life cycle assessment. Agricultural Systems.158:1-13.
• Alemu, A. W., Amiro, B. D., Bittman, S., MacDonald, D., and. Ominski, K.H. 2017. Greenhouse gas emission of Canadian cow-calf operations: A whole-farm assessment of 295 farms. Agricultural Systems.151:73–83.
• Guyader, J., Little, S. M., Kröbel, R., Benchaar, C., and Beauchemin, K. A. 2017. Comparison of greenhouse gas emissions from corn- and barley-based dairy production systems in Eastern Canada. Agricultural Systems.152: 38-46.
• Little, S. M., Benchaar, C., Janzen, H.H., Kröbel, R., McGeough, E. J., and Beauchemin, K. 2017. Demonstrating the effect of forage source on the carbon footprint of a Canadian dairy farm using whole-systems analysis and the Holos model: Alfalfa silage vs. corn silage. Climate. 5: 87-105.
• Amadi, C. C., Van Rees, K. C. J., and Farrell, R. E. 2016. Greenhouse gas mitigation potential of shelterbelts: estimating farm-scale emission reductions using the Holos model. Canadian Journal of Soil Science. 97(3):353–367.
• Chai, L., Kröbel, R., MacDonald, D., Bittman, S., Beauchemin, K. A., Janzen, H. H., McGinn, S. M., and Vanderzaag, A. 2016. An ecoregion-specific ammonia emissions inventory of Ontario dairy farming: Mitigation potential of diet and manure management practices. Atmospheric Environment.126:1-14.
• Kröbel, R., Bolinder, M. A., Janzen, H. H., Little, S. M., Vandenbygaart, A. J., and Kätterer, T. 2016. Canadian farm-level soil carbon change assessment by merging the greenhouse gas model Holos with the Introductory Carbon Balance Model (ICBM). Agricultural Systems. 143:76–85.
• Legesse, G., Beauchemin, K. A., Ominski, K. H., McGeough, E. J., Kroebel, R., MacDonald, D., Little, S. M., and McAllister T. A. 2016. Greenhouse gas emissions of Canadian beef production in 1981 as compared with 2011. Animal Production Science. 56(3):153-168.
• Legesse, G., Little, S. M., Beauchemin, K. A., Ominski, K. H, McGeough, E. J., Kröbel, R., MacDonald, D., and McAllister, T. A. 2016. A shrinking beef carbon footprint: Comparing greenhouse gas emissions of Canadian beef production between 1981 and 2011. LCA Food 2016: 10th International Conference on Life Cycle Assessment of Food 2016, Dublin, Ireland, October 19-21, 2016. (Presentation)
• Alemu, A., Little, S., Hao, X., Iwaasa, A., Baron, V., Chai, L., Janzen, H., Beauchemin, K., Thompson, D., and Kröbel, R. 2015. Application of life cycle assessment approach to beef production systems in the Canadian prairies: impacts of grazing management. LCA 15: LCA XV – A Bright Green Future Conference, Vancouver, BC, October 6-8, 2015. (Presentation)
• Chai, L., Kröbel, R., Beauchemin, K. A., MacDonald, D., Janzen, H. H., McGinn, S., and Bittman, S. 2015. Greenhouse gases and ammonia emissions from grazing beef cattle in Alberta and Ontario Canada. Canadian Society for Bioengineering Conference /CSBE /SCGAB 2015 Annual Conference, Edmonton, AB, July 5-8, 2015. (Presentation)
• Chai, L., Kröbel, R., MacDonald, D., Bittman, S., Beauchemin, K. A., Janzen, H. H., and McGinn, S. 2015. Developing nitrogen loss fractions for beef and dairy cattle manure storage systems in Canadian ecoregions: a comparison between West and East. Canadian Society for Bioengineering Conference/CSBE/SCGAB 2015 Annual Conference, Edmonton, AB, July 5-8, 2015. (Presentation)
• Church, J. S., Raymond, A. F., Moote, P. E., Van Hamme, J. D., and Thompson, D. J. 2015. Investigating the carbon footprint of cattle grazing the Lac du Bois Grasslands of British Columbia. Journal of Ecosystems and Management. 15(1):1–14.
• Kröbel, R., Janzen, H. H., Ellert, B. H., Beauchemin, K. A., and McAllister, T. A. 2015. Agriculture is neither the culprit nor the solution to Climate Change. Our Common Future under Climate Change Conference, Paris, France, July 7-10, 2015. (Poster)
• Kröbel, R., Li, S., Little, S. M., Vanin, C., and Janzen, H. H. 2015. Calculating greenhouse gases from the Black-Brook watershed, New Brunswick, using the Holos model. On Sustainability 2015, Copenhagen, Denmark, January 21-23, 2015. (Presentation)
• Little, S., Beauchemin, K., Benchaar, C., Chai, L., Janzen, H., Kröbel, R., McGeough, E., and VanderZaag, A. 2015. Demonstrating the effect of diet on the carbon footprint of a Canadian dairy scenario using whole-systems analysis and the Holos model: corn silage vs. alfalfa silage. LCA 15: LCA XV – A Bright Green Future Conference, Vancouver, BC, October 6-8, 2015. (Presentation)
• Martel, M., Kröbel, R., Hrapovic, L., Janzen, H., McConkey, B., Glenn, A., and Wilson, H. 2015. A Canadian water budget model for water footprint assessment of crop production. IUSS-CSSS-AQSSS 2015 Meeting, Montreal, QC, Canada, July 5-10, 2015. (Poster)
• Hünerberg, M., Little, S. M., Beauchemin, K. A., McGinn, S. M., O’Connor, D., Okine, E. K., Harstad, O. M., Kröbel, R. and McAllister, T. A. 2014. Feeding high concentrations of corn dried distillers’ grains decreases methane, but increases nitrous oxide emissions from beef cattle production. Agricultural Systems. 127:19-27.
• Beauchemin, K. A., Little, S. M., and Basarab, J. 2013. Genetic selection for residual feed intake to reduce GHG emissions from beef production in Canada – Evaluation using farm-based life cycle assessment. 2013 Greenhouse Gases and Animal Agriculture Conference, Dublin, Ireland, June 23-26, 2013. (Presentation)
• Hünerberg, M., Little, S. M., Beauchemin, K. A., McGinn, S. M., Harstad, O. M., Okine, E. K., McAllister, T. A. 2013. Farm-based life cycle assessment of greenhouse gas emissions from beef cattle fed dried distillers' grains plus solubles. 2013 CSAS-CMSA Joint Annual Meeting, Banff, AB, June 18-20, 2013. (Presentation)
• Kröbel, R., Janzen, H., Little, S., and Li, S. 2013. Preliminary Holos model assessment of GHG emissions from crop production in the Black-Brook watershed, NB, during the years 1988 – 1997. Canadian Society of Soil Science/ Manitoba Soil Science Society/ Canadian Society of Agricultural and Forest Meteorology Joint Meeting, Winnipeg, MB, June 22-25, 2013. (Presentation)
• McGeough, E. J., Little, S. M., Janzen, H. H., McAllister, T. A., McGinn, S. M., and Beauchemin, K. A. 2013. Greenhouse gas emissions from dairying in Eastern Canada – Effects of varying dairy cow replacement rate. 2013 Canadian Society of Animal Science (CSAS) - Canadian Meat Science Association (CMSA) Joint Annual Meeting, Banff, Alberta, June 18-20, 2013. (Presentation)
• McGeough, E. J., Little, S. M., Janzen, H. H., McAllister, T. A., McGinn, S. M. and Beauchemin, K. A. 2013. Greenhouse gas emissions from dairying in Eastern Canada – Effects of varying dairy cow replacement rate. 2013 Greenhouse Gases and Animal Agriculture Conference, Dublin, Ireland, June 23-26, 2013. (Presentation)
• Beauchemin, K. A., Janzen, H. H., Little, S. M., McAllister, T. A., and McGinn, S. M. 2012. Estimating the carbon footprint of beef production in western Canada. Prairie Post -Bull Breeders. (February:36 pages).
• Bonesmo, H., Little, S. M., Harstad, O. M., Beauchemin, K. A., Skelvag, A. O., and Sjelmo, O. 2012. Estimating farm-scale greenhouse gas emission intensity of pig production in Norway. Acta Agriculturae Scandinavica. Section A – Animal Science 62(4):318-325.
• Kroebel, R., Janzen, H. H., Beauchemin, K. A., Bonesmo, H., Little, S. M., and McAllister, T. A. 2012. A proposed approach to estimate and reduce the environmental impact from whole farms. Acta Agriculturae Scandinavica. Section A – Animal Science 62(4):225-232.
• McGeough, E. J., Little, S. M., Janzen, H. H., McAllister, T. A., McGinn, S. M., and Beauchemin, K. A. 2012. Life cycle assessment of greenhouse gas emissions from dairy production in Eastern Canada: A case study. Journal of Dairy Science. 95(9):5164-5175.
• Beauchemin, K. A., Janzen, H. H., Little, S. M., McAllister, T. A. and McGinn, S. M. 2011. Mitigation of greenhouse gas emissions from beef production in western Canada – Evaluation using farm-based life cycle assessment. Animal Feed Science and Technology. 166 &167:663-677.
• Beauchemin, K. A., McGeough, E. J., Little, S. M., Janzen, H. H., McAllister, T. A., McGinn, S. M., and Maclean, K. 2011. The Holos Model: reflections on progress and future plans. Norway, June 2011. (Presentation)
• Beauchemin, K. A., Janzen, H. H., Little, S. M., McAllister, T. A. and McGinn, S. M. 2010. Life cycle assessment of greenhouse gas emissions from beef production in western Canada: A case study. Agricultural Systems. 103(6):371-379.
• Beauchemin, K. A., Janzen, H. H., Little, S. M., McAllister, T. A. and McGinn, S. M. 2010. Mitigation of greenhouse gas emissions from beef production in Canada - Life cycle analysis using Holos. Greenhouse Gases and Animal Agriculture Conference, Banff, AB, October 3-8, 2010. (Presentation)
• Reducing methane emissions from livestock. 2010. Agriculture and Agri-Food Canada, Ottawa, ON.
• Little, S. M., Maclean, K., and Barbieri, J. 2010. Holos: A tool to estimate and reduce GHGs from farms. The model and the tools. Greenhouse Gases and Animal Agriculture Conference, Banff, AB, October 3-8, 2010. (Presentation)
• Holos: greenhouse gas (GHG) software for farms. 2009. Agriculture and Agri-Food Canada, Ottawa, ON.
• Stewart, A. A., Little, S. M., Ominski, K. H., Wittenberg, K. M., and Janzen, H. H. 2009. Evaluating greenhouse gas mitigation practices in livestock systems: an illustration using the whole-farm approach. The Journal of Agricultural Science. 147(4):367-382.
• Janzen, H. H., Desjardins, R. L., Rochette, P., Boehm, M., and Worth, D. (Eds). 2008. Better Farming Better Air: A scientific analysis of farming practice and greenhouse gases in Canada. Agriculture and Agri-Food Canada: Ottawa, ON, Canada. 146 pages.
• Little, S. M., Lindeman, J., Maclean, K., and Janzen, H. H. 2008. Holos - A tool to estimate and reduce GHGs from farms. Methodology and algorithms for Version 1.1. x. Agriculture and Agri-Food Canada, Ottawa, Ontario, ON, Canada.158 pages.
• Janzen, H. H., Angers, D. A., Boehm, M., Bolinder, M., Desjardins, R. L., Dyer, J. A., Ellert, B. H., Gibb, D. J., Gregorich, E. G., Helgason, B. L., Lemke, R., Massé, D., McGinn, S. M., McAllister, T. A., Newlands, N., Pattey, E. , Rochette, P. , Smith, W., VandenBygaart, A. J. , and Wang, H. 2006. A proposed approach to estimate and reduce net greenhouse gas emissions from whole farms. Canadian Journal of Soil Science. 86(3):401–418.