Organic farming can yield up to three times as much food as conventional farming on the same amount of land---according to new findings which refute the long-standing assumption that organic farming methods cannot produce enough food to feed the global population.
Researchers from the University of Michigan found that in developed countries, yields were almost equal on organic and conventional farms. In developing countries, food production could double or triple using organic methods, said Ivette Perfecto, professor at U-M's School of Natural Resources and Environment, and one the study's principal investigators. Catherine Badgley, research scientist in the Museum of Paleontology, is a co-author of the paper along with several current and former graduate and undergraduate students from U-M.
"My hope is that we can finally put a nail in the coffin of the idea that you can't produce enough food through organic agriculture," Perfecto said.
In addition to equal or greater yields, the authors found that those yields could be accomplished using existing quantities of organic fertilizers, and without putting more farmland into production.
The idea to undertake an exhaustive review of existing data about yields and nitrogen availability was fueled in a roundabout way, when Perfecto and Badgley were teaching a class about the global food system and visiting farms in Southern Michigan.
"We were struck by how much food the organic farmers would produce," Perfecto said. The researchers set about compiling data from published literature to investigate the two chief objections to organic farming: low yields and lack of organically acceptable nitrogen sources.
Their findings refute those key arguments, Perfecto said, and confirm that organic farming is less environmentally harmful yet can potentially produce more than enough food. This is especially good news for developing countries, where it's sometimes impossible to deliver food from outside, so farmers must supply their own. Yields in developing countries could increase dramatically by switching to organic farming, Perfecto said.
While that seems counterintuitive, it makes sense because in developing countries, many farmers still do not have the access to the expensive fertilizers and pesticides that farmers use in developed countries to produce those high yields, she said.
After comparing yields of organic and convention farms, the researchers looked at nitrogen availability. To do so, they multiplied the current farm land area by the average amount of nitrogen available for production crops if so-called "green manures" were planted between growing seasons. Green manures are cover crops which are ploughed into the soil to provide natural soil amendments instead of synthetic fertilizers. They found that planting green manures between growing seasons provided enough nitrogen to farm organically without synthetic fertilizers.
Organic farming is important because conventional agriculture---which involves high-yielding plants, mechanized tillage, synthetic fertilizers and biocides---is so detrimental to the environment, Perfecto said. For instance, fertilizer runoff from conventional agriculture is the chief culprit in creating dead zones---low oxygen areas where marine life cannot survive. Proponents of organic farming argue that conventional farming also causes soil erosion, greenhouse gas emission, increased pest resistance and loss of biodiversity.
For their analysis, researchers defined the term organic as: practices referred to as sustainable or ecological; that utilize non-synthetic nutrient cycling processes; that exclude or rarely use synthetic pesticides; and sustain or regenerate the soil quality.
Perfecto said the idea that people would go hungry if farming went organic is "ridiculous."
"Corporate interest in agriculture and the way agriculture research has been conducted in land grant institutions, with a lot of influence by the chemical companies and pesticide companies as well as fertilizer companies---all have been playing an important role in convincing the public that you need to have these inputs to produce food," she said.