Comparison of Organic and Conventional Crops at the Neely-Kinyon Long-term Agroecological Research (LTAR) Site, 2004

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 randomized 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 (CS-O/A-A), and Soybean-Wheat (S-W). Variety selection and planting methods in 2004 were as follows: Pioneer 34D71 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 30,200 seeds/acre in conventional plots, on May 17, 2004. Schillinger 240F.Y soybeans were planted at a depth of 2 in. in organic and conventional plots at a rate of 190,000 seeds/acre on June 4, 2004. ‘Wesley’ winter wheat was planted on October 13, 2003, at 100 lb/acre and red clover was frost-seeded into the wheat plots on March 12, 2004, at a rate of 14 lb/acre. All plots were harrowed on March 25. On March 25, 2004, ‘Jay’ oats were underseeded with Pioneer 54H91 leafhopper-tolerant alfalfa at a depth of 0.5 in. at a rate of 3.0 bushels/acre and 16 lb/acre, respectively. Following harvest of the organic corn plots in 2003, winter rye was notill drilled at a rate of 1 bushel/acre on October 15, 2003. Hoop-house swine compost was applied to organic corn plots at a rate of 12 tons/acre and 4 tons/acre to oat plots on March 24. Conventional corn plots were fertilized on May 19 with 32% urea at 160 lb/acre N. Soil in corn plots was sampled on July 7, 2004, and analyzed for late-spring nitrate content by the USDA-ARS National Soil Tilth Laboratory, Ames, IA. Conventional corn plots received applications of 0.67 oz/acre of Accent and 1 pt/acre of Buctril on June 14, 2004. Conventional soybeans received applications of 1.44 oz/acre of Pursuit, 7 oz/acre of Select, and 2 lbs/acre of AMS. Conventional soybean plots were cultivated on June 4, 23, and July 20. Organic soybean plots were cultivated on June 4, 23, and July 12, and rotary hoed on June 16, 28, and July 6. Conventional corn plots were cultivated on June 28, and organic corn plots were cultivated on June 8, 17, and 28. Corn stands were counted on June 15 and soybean stands on June 22. Weed counts were enumerated in corn plots on June 15 and July 23 and in soybean plots on June 22 and July 6 using square meter quadrats at three randomly selected areas within a plot. Corn borer populations were monitored on July 6. Soybean plots were sampled for bean leaf beetles on September 7. Corn stalk nitrate samples were collected on October 4, and soybean cyst nematode sampling was completed on October 11. Samples (200 g) were collected from each corn and soybean plot for grain quality analysis, which was conducted at the ISU Grain Quality Laboratory, Ames, IA.