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The Farm Fieldwork and Fossil Fuel Energy and Emissions (F4E2) model was upgraded and then re-verified using the 1996 Farm Energy Use survey (FEUS). The revised model was used to evaluate trends in fossil fuel-based GHG emissions from 1986 to 2001 by using Agricultural Census data to integrate farm-level simulations over national areas of different land uses and tillage practices. The most significant upgrade was the addition of a sub-model for forage harvesting which was integrated nationally using just the areas in tame hay. Accordingly, F4E2 farm-level simulations for annual crops were integrated over just those farm areas instead of all cropland. National estimates of diesel fuel consumption agreed with FEUS within half a percent. Fossil fuel GHG emissions on Canadian farms dropped by 22% from 1986 to 2001 and by 14% from 1991 to 2001. By far the greatest changes have occurred in the Prairies where the most noticeable shift toward reduced tillage has taken place and in spite of less land in summer fallow. In this analysis, the net effect of those measures which increase soil carbon sequestration is toward reduced fossil fuel GHG emissions and energy consumption on Canadian Farms. [ABSTRACT FROM AUTHOR]

Energy must be considered in the assessment of greenhouse gas (GHG) emissions from agriculture, even though, compared to methane and nitrous oxide emissions, it is a smaller source which is usually attributed to other sectors such as transportation and manufacturing. This communication summarises some analytical methods that have been developed to inventory energy based GHG emissions from Canadian agriculture. Farm energy survey data provided verification for these methods. Agricultural energy can be classified as either direct or indirect. Direct energy includes on-farm fossil fuel and electricity use, while indirect energy includes all the manufacturing of farm inputs. The main indirect energy uses are synthetic fertiliser supply and farm machinery production. Farm field work and crop drying account for most of the fossil fuel used on the farm. The energy budget for two typical Canadian farms estimated with the methods described here demonstrates the huge impact of regional and farm type differences on farm level GHG emissions. [ABSTRACT FROM AUTHOR]