Ontario Grain Farmer April/May 2024

18 Sustainability Quantifying GHG emissions DRIVERS, APPROACHES, AND FARM INSIGHTS Lisa Ashton AGRICULTURAL PRODUCTION IS A SOURCE AND SINK OF GREENHOUSE GAS (GHG) EMISSIONS. Determining if a farm, region, or even a country’s agricultural sector is a net source or sink of GHG emissions requires data collection and analysis of a combination of factors, including local climatic conditions, soil type, production systems, and adoption rates of management practices such as tillage and irrigation. Taking stock of the pluses and minuses in GHG emissions and trends over time is critical and, in some cases, a required action across economic sectors, including transportation, waste, and agriculture. Quantifying GHG emissions from agricultural production is increasingly becoming a common practice among food and agriculture companies, governments, investors and banks, and farmers. The reasons for quantifying GHG emissions and carbon sequestration in agriculture are diverse and growing, including: • Improve supply chain traceability • Track progress against climate and nature targets • Identify areas of progress and hotspots to inform decision-making and investments • Demonstrate to stakeholders along supply chains and in policy development that the agriculture sector is taking action to better understand and mitigate impacts on climate change and nature • Make credible claims about the sustainability of commodities and products (e.g., carbon footprinting) • Develop new revenue streams through market-based mechanisms Amadou Thiam, engineering specialist at the Ontario Ministry of Agriculture, Food and Rural Affairs (OMAFRA), says that “quantifying GHG emissions can be a useful exercise for farmers to develop a baseline, as areas of progress and hotspots are not always what we may assume.” Thiam shares that grain farmers in Ontario are doing a lot of great things when it comes to mitigating GHG emissions. The key areas that grain farmers may need to focus on for their GHG emissions are fertilizer application and fuel use. QUANTIFYING ON-FARM GHG EMISSIONS AND CARBON SEQUESTRATION There are direct and indirect methods to quantify GHG emissions and soil carbon on farms. Direct measurements include soil sampling and using static chamber-based methods to quantify the impacts of practices and production systems on soil carbon and GHG emissions on site. Indirect measurement approaches are primarily calculation-based but are informed by direct measurement approaches to ensure that the calculations closely represent actual observations. Indirect and direct approaches depend on each other to provide assurance to estimates, improve accuracy, and scale our ability to quantify GHG emissions. When asked about approaches to building an accurate QUANTIFICATION TYPE DESCRIPTION QUANTIFICATION APPROACHES EXAMPLE OF FARM-LEVEL ROLE IN QUANTIFICATION DIRECT MEASUREMENT Measurement-based approaches: Soil sampling and using static chamber-based methods to quantify the impacts of practices and production systems on soil carbon and GHGs. Physically taking measurements in the field and sending samples to a lab for analysis. Note: Some direct measurement tools, such as chamber-based methods, are generally only suitable in research settings due to equipment costs and expertise requirements. INDIRECT MEASUREMENT Activity-based calculation approaches: Methods that multiply activity data that describes an on-farm practice (e.g., manure application) by a coefficient that was developed through research trials to characterize the estimated GHG impact of the respective activity (e.g., 1% of N application is released as N2O emissions). Participating in surveys that collect information on practice and technology adoption. Note: This approach can be used to develop carbon intensity scores of crop production. Model-based calculation approaches: Methods that use mathematical modelling to estimate GHG emissions using input variables (e.g., tillage practices) and fixed parameters (e.g., soil type) adapted to the regional and production system context. Using model-based tools to estimate on-farm emissions and participating in surveys and research that collect information on practice and technology adoption. Note: This approach also relies on activity data and research to improve model calibration. Adapted from GHG Protocol’s draft Land Sector and Removals Guidance. Note: This table is not exhaustive of all approaches.