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Twenty-one Year Study Documents
the Many Benefits of Organic Agriculture

Organic farmers have long touted their methods as a more benign way to nourish the world, ideally producing good crop yields with minimal impact on the environment and on ecological factors such as soil fertility. However, few rigorous studies have looked at the long-term yields and environmental effects of organic farming. The European Union reportedly has up to 8% of its agricultural land under organic management. However, organic farms remain a niche operation.

Now a new report brings encouraging news for organic fans. A team led by agronomists Paul Mäder of the Research Institute of Organic Agriculture in Frick, Switzerland, and David Dubois of the Swiss Federal Research Station for Agroecology and Agriculture in Zürich reports the results of the longest and most comprehensive study to date comparing organic and conventional farming, measuring many aspects of crops and soil over 21 years.

The bottom line: Organic farms can be nearly as productive as regular farms for some crops, and they leave soils healthier. Organic soil management improves soil structure by increasing soil activity, thus reducing the risk of erosion. The study also demonstrates that in addition to advantages in soil fertility management, organic farming enhances biodiversity. Organic management results in farms hosting more kinds of beneficial insects.

The study also conclusively demonstrates that for most crops, organic plots are more energy efficient per unit crop. Because no synthetic fertilizer had to be produced or applied, growing organic crops requires less energy than conventional crops--up to 56% less energy per unit yield. Nutrient inputs (N, P, K) in the organic systems were 34 to 51% lower than in the conventional systems, whereas mean crop yield was only 20% lower over a period of 21 years indicating an efficient production.

The best performing organic crop was winter wheat, which stacked up at about 90% of the conventional harvest. Potatoes fared the worst with about 62% of conventional yields, mainly due to potato blight and potassium deficiency. The yields are impressive given that the organic plants received less than half the nutrients given to conventional plots. "To add that much less fertilizer and still get 80% of the conventional yields is outstanding," says John Reganold, soil scientist at Washington State University, Pullman.

The team also found evidence that nutrient-cycling microbes are more diverse, plentiful, and efficient in organic soil, making more nutrients available to plants. More microbes are known to improve soil structure, and Mäder's team found another benefit: higher yields in organic plots that boasted the maximum microbes. Microbial activity increases under long term organic management. More study is needed on the effect long term organic management has on yields.

Soils did appear to be healthier in organic plots, with 40% more roots colonized by fungi that assist with plant nutrition. Earthworms were up to three times more abundant, and there were twice as many spiders and other pest-eating arthropods.

"This study is as complete a picture as we have from anywhere," says Phil Robertson, an agricultural ecologist at Michigan State University, East Lansing. Reganold agrees , "This gives more credibility to organic systems."

Excerpts taken from the research report at http://www.fibl.ch/engl/research/soil-ecology/dok/index.html and Greenthumb May 2002.

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