Canadian greenhouse gas mitigation options in agriculture
In 1991, on farm management practices contributed 57.6 Tg CO2 equivalent in greenhouse gas emissions, that is, about 10% of the anthropogenic GHG emissions in Canada. Approximately 11% of these emissions were in the form of CO2, 36% in the form of CH4 and 53% in the form of N2O. The CO2 emissions were from soils; CH4 emissions were from enteric fermentation and manure, and N2O emissions were primarily a function of cropping practices and manure management. With the emissions from all other agricultural practices included, such as the emissions from fossil fuels used for transportation, manufacturing, food processing etc., the agricultural sector's contributions were about 15% of Canada's emissions. In this publication, several options are examined as to their potential for reducing greenhouse gas emissions. These involve soil and crop management, soil nutrient management, improved feeding strategies, and carbon storage in industrial by-products. The Canadian Economic Emissions Model for Agriculture (CEEMA) was used to predict the greenhouse gas emissions for the year 2010, as well as the impact of mitigation options on greenhouse gas emissions from the agricultural sector. This model incorporates the Canadian Regional Agricultural sub-Model (CRAM), which predicts the activities related to agriculture in Canada up to 2010, as well as a Greenhouse Gas Emissions sub-Model (GGEM), which estimates the greenhouse gas emissions associated with the various agricultural activities. The greenhouse gas emissions from all agricultural sources were 90.5 Tg CO2 equivalent in 1991. Estimates based on CEEMA for the year 2010 indicate emissions are expected to be 98.0 Tg CO2 equivalent under a business as usual scenario, which assumes that the present trends in management practices will continue. The agricultural sector will then need to reduce its emissions by about 12.9 Tg CO2 equivalent below 2010 forecasted emissions, if it is to attain its part of the Canadian government commitment made in Kyoto. Technologies focusing on increasing the soil carbon sink, reducing greenhouse gas emissions and improving the overall farming efficiency, need to be refined and developed as best management practices. The soils carbon sink can be increased through reduced tillage, reduced summer fallowing, increased use of grasslands and forage crops, etc. Key areas for the possible reduction of greenhouse gas emissions are improved soil nutrient management, improved manure storage and handling, better livestock grazing and feeding strategies, etc. The overall impact of these options is dependent on the adoption rate. Agriculture's greenhouse gas reduction commitment could probably be met if soils are recognized as a carbon sink under the Kyoto Accord and if a wide range of management practices are adopted on a large scale. None of these options can currently be recommended as measures because their socio-economic aspects have not been fully evaluated and there are still too many uncertainties in the emission estimates.