Organic vs. Conventional Farming: Which Method Uses Less Energy?
After a recent study released by Dena Brevata and her team of researchers at Stanford argued that there is little evidence of health benefits from eating organic foods, many were left to wonder what the other benefits of eating organic might be? What differences might there be in energy use or land use between conventional and organic farming methods?
While Brevata clarified that eating organic foods does seem to result in a lower pesticide exposure, she pointed out that there is currently no direct link between that data and personal health.
In terms of land use, it’s been shown that conventional production can often produce more food on less land, although some organic methods like biointensive farming use innovative organic growing methods to grow more food on less land. But with caloric demand rising worldwide, we may not have the amount of open space needed for primarily organic growing methods without sacrificing ecologically important zones of high biodiversity.
So, what about energy use then? A recent Washington Post article by William Wan analyzes the amount of energy used in both methods of food production. His conclusions show that organic does use quite a bit less energy, though not for the reasons people might generally expect.
Wan turned to the Rodale Institute, a nonprofit which has dedicated more than 30 years to researching conventional chemical farming methods alongside organic methods. Their Farming Systems Trial is the longest running study of its kind in the United States. Through this study, they have found that organic yields match conventional and outperform them in times of drought or environmental stress.
The Rodale Institute has also found that farming approximately 2.5 acres of organic corn requires 10,150 megajoules of energy (equivalent to about 78 gallons of gasoline). On the flip side, the same size plot using conventional methods to grow corn requires 17,372 megajoules of energy, which is over 70 percent more than the organic crop.
Surprisingly it’s not the pesticides and herbicides used in conventional farming that make up the bulk of this energy differential. It’s actually the nitrogen-based fertilizer used in conventional growing techniques. As the Rodale Institute explains, “The manufacture and transport of synthetic nitrogen requires a tremendous amount of oil.”
In the organic growing model, nitrogen is usually sourced from animal manure and through planting cover crops in the off season in order to fix nitrogen in the soil. The cover crops additionally provide more food for market.
With issues like this past summer’s drought in the Midwest, other severe weather events affecting agriculture and the rise of herbicide resistant superweeds, the energy differential and the resilience of organic vs. conventional farming may shift in the future. What this ultimately highlights is the complexity of our food system, and the reality that the choices between organic or conventional, local or produced elsewhere are not always black and white. There are always nuances when considering which methods of production are best for people and best for the environment.
Calorie demand is rising worldwide, and as a result we will need to find creative ways to grow more food with less space and less energy intensive inputs. Another recent study known as the Marsden Farm Study showed that a hybrid of organic and conventional growing methods may be a good way forward.
The Washington Post article also points out the critical reality that, according to some estimates, farming accounts for only 35 percent of the energy embedded in food, with the other 65 percent going to transportation, cooking and disposal of waste. So, in order to make a significant impact on the fuel used in our food systems, we will have to address more efficient farming methods as well as more efficient transportation and reduction of waste along the production cycle through to consumption.
Photo via (cc) Flickr user RuudMorijn