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Ames, Iowa 50011-3630
(515) 294-9915


Kathleen Delate, Agronomy and Horticulture, (515) 294-7069,
Jean McGuire, Continuing Education and Communications Services, (515) 294-7033,

ISU Releases Organic Transition Research Results

AMES, Iowa -- Iowa State University (ISU) Extension researcher, Kathleen Delate, associate professor, Agronomy and Horticulture, and Cynthia Cambardella, USDA-ARS soil scientist, are comparing yields, pest status and soil quality during the transition from conventional to organic production in Iowa. The results of this study were published in the September-October edition of the Agronomy Journal, Vol. 96: 1288-1298.

This study and other research projects on organic flax, apples and squash will be discussed at the Fourth Annual ISU Organic Conference to be held Nov. 1.

In the long-term study at the ISU Neely-Kinyon Research Farm in southwest Iowa, identical non-GMO hybrid varieties of corn and soybeans are being grown using conventional and organic methods.

In the conventional plots, an alternating cycle of corn and soybeans is being grown. In the organic plots, oats and alfalfa are added to the corn-soybean rotation, and the third organic rotation consists of soybean and winter wheat with under-seeded crop of clover. Each crop in each rotation is planted every year.

The organic plots were established in 1998 at the request of area farmers to begin a long-term comparison on the effects of organic practices.

"In the first three years of transition, we found that soybean yields were not statistically different between conventional and organic, and that organic yellow dent feed corn yields were equivalent in organic and conventional plots," Delate said.

"However, in the fourth year the organic corn yield and soybean yield in one treatment surpassed the conventional yield. Those yields were in fields that followed two years of alfalfa. The only year organic corn yield was less than conventional was in 1999, when a white milling variety was grown," she said.

Pest insect populations were low in both systems during the transition, while grain quality was high.

Cambardella, works on the soil quality aspects of the research. "One of the questions you get from farmers looking to transition to an organic system is: 'Will there be adequate fertility in the system to get me through the transition?' " she said.

"We were able to show that soils at the Neely-Kinyon Farm could support organic crop yields similar to conventional systems during the three-year transition."
The organic corn crop was fertilized with composted manure, following the practice used by local organic farmers. Additional management practices include weed control through tillage and the use of weed-suppressing crops.

Because the organic system had a higher return than the conventional system, Delate believes that the organic crop system is definitely an economically competitive system and should be looked at very positively as an alternative to conventional systems.

This research, supported by the Leopold Center for Sustainable Agriculture and the USDA Initiative for Future Agriculture and Food Systems Organic Agriculture Consortium, is gaining national recognition, and according to Rodale Press, "ISU leads the way in organic ag research and extension."

A copy of the Agronomy Journal article is available at:

Learn more about the Fourth Annual Organic Conference and other organic research articles at:

Read more about the Neely-Kinyon Farm and the ISU organic agriculture program at


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