Longest-term organic trials link Swiss, Rodale institutes
Visit highlights soil benefits of long-term sustainable systems

Posted August 10, 2006

Different approaches to studying the comparative impacts of organic and other cropping systems in side-by-side plots give soil specialists lots to talk about. That was clear when Paul Mader, PhD, spent a day recently at The Rodale Institute.

Mader is the research leader of the DOK (Biodynamic, Organic and Conventional) crop systems trial in Therwil, Switzerland, the world’s longest-running trial comparing organic and conventional farming systems. A plant pathologist by training, Dr. Mader obtained a PhD at University of Basel in 1988. Since 1989, he has been with FiBl (the Organic Research Institute in Switzerland), which runs the DOK trial. FiBl has 60 scientists and 60 support staff working on organic agriculture in Europe, Africa and India, with an annual budget of about $20 million.

Mader, who was in Pennsylvania to attend the World Soil Science Congress in Philadelphia, said the European Union is quite supportive of organic agriculture. In his own home country, he said, 6,500 commercial organic farms cover nearly 11 percent of all arable acreage. While visiting The Rodale Institute, Mader spoke with staff and reviewed programs, then gave a seminar on soil life and crop highlights from the DOK trials and discussed the role of reduced tillage in organic farming.

Like the Rodale Institute’s long-term Farming Systems Trial—which began in 1981 compared to DOK’s start date of 1978—the Swiss trials mimic real farming practices. There are also about 250 farm collaborators. “Farmers helped to plant this experiment from the very beginning and still help us to guide the comparison trial,” said Dr. Mader. The DOK trials compare biodynamic, organic and conventional farming.

Besides leading the work on the historic farming systems trial, Mader is also the leader of a soil biology research team.

In a study accepted for publication in Science magazine, Mader explains how an organic farming approach that reduces inputs by 50 percent can maintain 80 percent of conventional yields while both improving soil biological diversity and reducing environmental impacts of agricultural production. Work at The Rodale Institute, which is geared to optimize organic inputs through compost and cover crops, has been of interest for showing no yield decrease for organic production compared to conventional farming, along with substantial gains in soil organic matter.

The land where the DOK trials are taking place was previously in conventional grass and clover, Dr. Mader said. “It could be that we are still in a conversion process and that equilibrium has not yet been reached.”

Some key findings of the DOK study:

  • Erosion was less of a factor in the biodynamic and organic systems than in the conventional system.
  • A close correlation exists between aggregate stability and soil microbial biomass.
  • Organic material decomposed more rapidly in a biodynamic system compared to a mineral-based system.
  • A greater diversity of the microbial soil population and larger animal species—such as earthworms and insects—had a positive impact on plant growth and vigor, soil structure and carbon cycling.