Summerfallow reduction on the prairies and mitigation of greenhouse gas emissions
Previous research has shown that in relatively moist areas of Saskatchewan the use of crop rotations that exclude summerfallow is desirable from the perspectives of C sequestration and reduced greenhouse gas (GHG) emissions as well as from the soil quality perspective. In this study, the Canadian Economic and Emissions Model of Agriculture (CEEMA) was used to evaluate, based on a systems approach, the total reduction in greenhouse gas emissions associated with reduced summerfallow. Results show that analyses based only on a partial set of information – reduction in the area of summerfallow – overestimate the mitigation effect. Since the land that is taken out of summerfallow does not remain idle, but is used in crop or forage production, the GHG emissions of the alternative land use must also be considered. Crop production requires farm inputs, such as N fertilizers, which contribute to the total emissions of greenhouse gases from agriculture. The conversion of summerfallow to crop production, based on a reduction in summerfallow area by 50%, decreased GHG emissions by one megatonne only if the C sequestration benefits of reduced summerfallow are counted as an offset. If the sink is not counted, the GHG emissions increased as land shifted from summerfallow to crop production. However, a considerable degree of uncertainty exists, and more research is needed on this aspect of mitigation.
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