Greenhouse Gas Emissions From Canadian Agriculture: Estimates and Measurements

Canada produced 729 megatonnes of greenhouse gas (GHG) emissions in 2018 and approximately 10 per cent of that came from the country’s agricultural sector. Different farming operations produce varying amounts of GHGs, whether they are small animal or crop farms, or large beef cattle operations. Besides field techniques, researchers are using models such as HOLOS – a Canadian whole-farm emissions model – and the Integrated Farm Systems Model, among others, to find ways to target emission sources without hampering a farm’s financial sustainability and production. Other models focus on simulating the productivity and impact of cropping systems on the environment, with the goal of estimating the level of emissions. Other models are used to derive management-driven soil carbon change factors. Carbon footprints vary for every subsector of agriculture and assessing them is a complex effort that involves accounting for every process that occurs throughout production. Methane and nitrous oxide are the main GHGs that agriculture emits at 38 and 36 per cent respectively, with carbon dioxide responsible for the remaining 26 per cent. GHGs arise from enteric fermentation of cattle, the application of synthetic and organic fertilizer, biomass decomposition, soil cultivation and tillage, mineralization of soil organic matter and manure, among other sources. There are many options available for reducing agricultural GHG emissions, depending on the type of farm operation. Soil carbon content can be increased and stored in the soil or in plants to cut CO2 losses to the atmosphere. Carbon storage can be achieved by using cover crops or mulches and switching from annual to perennial cropping, for example. No-till practices permit the soil to develop porosity with better moisture retention and organic matter buildup, creating a healthy environment for roots, microorganisms and fungi. Manure emissions can be managed by capturing CH4 (methane) and using it to generate heat and electricity. Manure piles can also be aerated to reduce emissions. Energy consumption from farm equipment can be reduced through sustainable practices such as reducing tillage, retaining residue and managing mixed-species forests, as well as reducing pesticide and fertilizer applications through diverse cropping systems. In addition to saving fuel consumption, sustainable practices minimize soil erosion. Other sustainable practices include avoiding clear-cutting, contour plowing and using mulches and compost to increase the soil’s carbon and nutrient content. Consumers can make a significant difference in reducing agricultural GHG emissions by making informed choices when purchasing food. Eating a balanced diet that includes a variety of sources of protein can contribute to reducing emissions. Multi-product farm systems that integrate cropping, dairy and beef production have a lower carbon footprint and higher production efficiencies compared to single-product farm systems.