UNIVERSITY PARK, Pa. – Organic soybean producers using no-till and reduced-tillage production methods that incorporate cover crops can achieve similar yields at competitive costs compared to tillage-based production.

That’s the conclusion of a new study by researchers at Pennsylvania State University. The findings are significant because they may contribute to increased sustainable domestic production of organic soybeans.

The experiment focused on finding ways to reduce the intensity or frequency of tillage or soil disturbance in organic field-crop production systems. It was conducted on certified-organic land at Penn State’s Russell Larson Agricultural Research Center. We compared tillage-based soybean production preceded by a cover crop mixture interseeded into corn. Reduced-tillage soybean production was preceded by a roller-crimped cereal-rye cover crop sown after corn silage.

The reduced-tillage soybean sequence resulted in 50 percent less soil disturbance compared to the tillage-based soybean sequence across study years. That offers promising substantial gains in water quality and soil conservation. Budget comparisons showed the reduced-tillage soybean sequence resulted in fewer input costs than the tillage-based soybean sequence. But the reduced-tillage system was about $46 per acre less profitable because of slightly less average yields.

Organic grain producers are interested in reducing tillage to conserve soil and reduce labor and fuel costs. We examined agronomic and economic tradeoffs associated with alternative strategies for reducing tillage frequency and intensity in a cover crop-soybean sequence within a corn–soybean-spelt organic-cropping system.

Weeds are a serious problem for organic growers of field crops because growers are unable to kill them with herbicides. We found that weed biomass didn’t differ between soybean-production strategies. That matters because tillage and cultivation are the primary methods used by organic producers to reduce weeds and other pests.

Tillage-based soybean production marginally increased grain yield by fewer than three bushels per acre compared with the reduced-tillage soybean system.

The study is the latest in a 15-year-long line of organic no-till research conducted in the college of agricultural sciences at Penn State and led by William Curran, professor emeritus of weed science. Although he retired last year he also participated in the study. Organic no-till field-crop research continues at Penn State with the direction of Wallace and entomologist Mary Barbercheck.

Finding ways to allow more domestic production of organic soybeans is a huge issue. More than 70 percent of the organic soybeans fed to organically produced poultry in the United States are imported. The organic soybeans come primarily from Turkey, India and Argentina.

There have been many cases of fraudulent imports. That has depressed premiums that U.S. producers receive because we’re being flooded with these imports.

The U.S. Department of Agriculture’s National Institute of Food and Agriculture through the Organic Agriculture Research and Extension Initiative grant program partially supported the research. The study recently was published in “Renewable Agriculture and Food Systems.” Visit cambridge.org/core/journals and search for "agronomic-and-economic-tradeoffs-between-alternative-cover-crop-and-organic-soybean-sequences" for more information.

John Wallace is an assistant professor of weed science at Pennsylvania State University. He led the research project on using cover crops in organic-soybean production.