Comparison of Organic and Conventional Crops at the Neely-Kinyon Long-term Agroecological Research (LTAR) Site, 2003

Materials and Methods The Neely-Kinyon LTAR site was established in 1998 to study the long-term effects of organic production in Iowa. Treatments at the LTAR site, replicated four times in a completely random design, include the following rotations: conventional Corn-Soybean (C-S), organic Corn-Soybean-Oats/Alfalfa (C-S-O/A), organic Corn-Soybean-Oats/Alfalfa-Alfalfa (C-S-O/AA), and Soybean-Wheat (S-W). Variety selection and planting methods were as follows: Pioneer 34M94 corn was planted at a depth of 1.75 in. as untreated seed at a rate of 32,000 seeds/acre in the organic plots and as treated seed at a rate of 30,000 seeds/acre in conventional plots, on May 23, 2003. Schillinger 240F.Y soybeans were planted at a depth of 2 in. in organic and conventional plots at a rate of 200,000 and 185,000 seeds/acre, respectively, on May 28, 2003. ‘Wesley’ winter wheat was planted on October 17, 2002, at 90 lb/acre and red clover was frost-seeded into the wheat plots on March 26, 2003, at a rate of 15 lb/acre. On April 1, 2003, ‘Reeves’ oats were underseeded with Pioneer 54H91 leafhoppertolerant alfalfa at a depth of 0.5 in. at a rate of 3.5 bushels/acre and 18 lb/acre, respectively. Following harvest of the organic corn plots in 2002, winter rye was no-till drilled at a rate of 1 bushel/acre on October 17, 2002. Hoop-house swine compost was applied to organic corn plots at a rate of 12 tons/acre on April 2, and 4 tons/acre to oat plots on March 31, 2003. Conventional corn plots were fertilized on May 27 with 28% urea at 150 lb/acre N. Soil in corn plots was sampled on June 19, 2003, and analyzed for late-spring nitrate content by the Iowa State University Agronomy Soils Laboratory, Ames, IA. Conventional corn plots received 1.75 oz/acre of Balance on May 27, and on June 27 received Accent at .67 oz/acre, Buctril at 1 pt/acre, NIS at 5 oz/acre, and AMS at 2 lbs/acre. Conventional soybeans received applications of Prowl (2.2 pt/acre) on May 30, and on June 27 received Pursuit at 1.44 oz/acre, Select ® at 7 oz/acre, and AMS at 2 lb/acre. Conventional soybeans also received one cultivation on July 22. Organic corn plots were harrowed on May 30, rotary hoed on June 6, 9, and 12, and cultivated on June 16 and July 1. Organic soybeans were harrowed on May 30, rotary hoed on June 6, 9 and 12, and cultivated on June 20, July 2 and 14. Corn stands were counted on June 11 and soybean plots on July 18. Weed counts were enumerated in corn plots on June 11 and July 9 and in soybean plots on June 18 and July 9 using square meter quadrants at three randomly selected areas within a plot. Corn borer populations were monitored on July 9. Soybean plots were sampled for bean leaf beetles on August 7. Soybean cyst nematode sampling was completed on September 24.