Iowa State University (ISU) Extension researcher and agronomy professor Kathleen Delate, and Cynthia Cambardella, a USDA-ARS soil scientist at the National Soil Tilth Lab at Ames, have a unique project going. They are comparing yields, pest status and soil quality during the transition from conventional to organic production in Iowa.
Results of this study were published in September-October edition of the Agronomy Journal. This study and other research projects on organic flax, apples and squash were discussed at the Fourth Annual ISU Organic Conference Nov. 1 in Ames.
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.
Long-term comparison of organic practices
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," says Delate.
"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 says.
Pest insect populations were low in both systems during the transition, while grain quality was high.
Adequate soil fertility with organic?
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 notes.
"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 USDA’s 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:
agron.scijournals.org/cgi.content/abstract/96/5/1288.
Learn more about the Fourth Annual Organic Conference and other
organic research articles at:
extension.agron.iastate.edu/organicag/.
Read more about the Neely-Kinyon Farm and the ISU organic agriculture
program at: www.newfarm.org/features/1004/delate/index.shtml.