Scenario modeling potential eco-efficiency gains from a transition to organic agriculture: life cycle perspectives on Canadian canola, corn, soy, and wheat production.
We used Life Cycle Assessment to scenario model the potential reductions in cumulative energy demand (both fossil and renewable) and global warming, acidifying, and ozone-depleting emissions associated with a hypothetical national transition from conventional to organic production of four major field crops [canola (Brassica rapa), corn (Zea mays), soy (Glycine max), and wheat (Triticum aestivum)] in Canada. Models of these systems were constructed using a combination of census data, published values, and the requirements for organic production described in the Canadian National Organic Standards in order to be broadly representative of the similarities and differences that characterize these disparate production technologies. Our results indicate that organic crop production would consume, on average, 39% as much energy and generate 77% of the global warming emissions, 17% of the ozone-depleting emissions, and 96% of the acidifying emissions associated with current national production of these crops. These differences were almost exclusively due to the differences in fertilizers used in conventional and organic farming and were most strongly influenced by the higher cumulative energy demand and emissions associated with producing conventional nitrogen fertilizers compared to the green manure production used for biological nitrogen fixation in organic agriculture. Overall, we estimate that a total transition to organic production of these crops in Canada would reduce national energy consumption by 0.8%, global warming emissions by 0.6%, and acidifying emissions by 1.0% but have a negligible influence on reducing ozone-depleting emissions.
School for Resource and Environmental Studies, Dalhousie University, Kenneth C. Rowe Management Building, 6100 University Avenue, Suite 5010, Halifax, NS, Canada B3H 3J5. nathanpelletier@dal.ca
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Pelletier
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Arsenault
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Tyedmers
D000383:Agriculture / Q000379:methods*; D029741:Brassica rapa / Q000378:metabolism; D004736:Energy-Generating Resources; D004787:Environmental Pollution / Q000032:analysis*; D005308:Fertilizers / Q000009:adverse effects* / Q000032:analysis; D017752:Greenhouse Effect; D008372:Manure; D008697:Methane / Q000009:adverse effects / Q000032:analysis; D009584:Nitrogen / Q000032:analysis / Q000378:metabolism*; D009609:Nitrous Oxide / Q000009:adverse effects / Q000032:analysis; D010126:Ozone; D013025:Glycine max / Q000378:metabolism; D014908:Triticum / Q000378:metabolism; D003313:Zea mays / Q000378:metabolism
D005308:Fertilizers; D008372:Manure; D010126:Ozone; D009609:Nitrous Oxide; D009584:Nitrogen; D008697:Methane