Evaluating greenhouse gas mitigation practices in livestock systems: an illustration of a whole-farm approach

Abstract

SU MMARYAs agriculture contributes about 0 . 08 of Canada's greenhouse gas (GHG) emissions, reducing agricultural emissions would significantly decrease total Canadian GHG output. Evaluating mitigation practices is not always easy because of the complexity of farming systems in which one change may affect many processes and associated emissions. The objective of the current study was to compare the effects of selected management practices on net whole-farm emissions, expressed in CO 2 equivalents (CO 2 e) from a beef production system, as estimated for hypothetical farms at four disparate locations in western Canada. Whole-farm emissions (t CO 2 e) per unit of protein output (t) of 11 management systems (Table 2) were compared for each farm using a model based, in part, on Intergovernmental Panel on Climate Change (IPCC) equations. Compared with the baseline management scenario, maintaining cattle on alfalfa-grass pastures showed the largest decrease (0 . 53-1 . 08 t CO 2 e/t protein) in emissions for all locations. Feeding lower quality forage over winter showed the greatest increase in emissions per unit protein on the southern Alberta (S.AB) and northern Alberta (N.AB) farms, with increases of 1 . 36 and 2 . 22 t CO 2 e/t protein, respectively. Eliminating the fertilization of forages resulted in the largest increase (4 . 20 t CO 2 e/t protein) in emissions per unit protein on the Saskatchewan (SK) farm, while reducing the fertilizer rate by half for all crops showed the largest increase (11 . 40 t CO 2 e/t protein) on the Manitoba (MB) farm. The findings, while approximate, illustrate the importance of considering all GHGs simultaneously, and show that practices which best reduce emissions may vary among locations. The findings also suggest merit in comparing emissions on the basis of CO 2 e per unit of protein exported off-farm, rather than on the basis of total CO 2 e or CO 2 e per hectare.

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Effect of farming practices for greenhouse gas mitigation and subsequent alternative land use on environmental impacts of beef cattle production systems

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Beneficial management practices and mitigation of greenhouse gas emissions in the agriculture of the Canadian Prairie: a review

“…and/or per unit of area occupied. Stewart et al (2009) compared whole-farm emissions per unit of protein output of 11 management systems based, in part, on equations recommended by IPCC. The authors showed that compared to the baseline management scenario, pasturing cattle on alfalfa-grass had the largest decrease (0.39 to 0.66 Mg CO 2 e (Mg protein) −1 ) in emissions for all locations.…”