Corn and Soybean Yield Response to Tillage, Rotation, and Nematicide Seed Treatment

Corn (Zea mays L.) and soybean [Glycine max (L.) Merr.] rotations are common production systems across the midwestern United States. However, the interactive effect of crop rotation, tillage, and nematicide seed treatments on the yield of both crops in the rotation system is not well understood. Field trials were conducted in a long-term crop rotation experiment during 2013 to 2015 to measure yield response of both corn and soybean to three factors: (i) tillage system (no-till [NT] and conventional), (ii) crop rotation frequency (14 sequences involving corn and soybean), and (iii) three nematicide seed treatments (a control, abamectin/Pasteuria nishizawae, and Bacillus firmus). Rotations that involved consecutive years of soybean exhibited the greatest nematode populations in the soil, whereas, consecutive years of corn resulted in lower nematode populations. No significant differences in nematode populations were observed among the other examined management practices. Conventional tillage resulted in up to 18% greater corn and 10% greater soybean yield than NT. Yearly crop rotation increased corn yield by 20% and soybean yield by 22% compared with continuous cropping. Seed treatment nematicides had no effect on corn and soybean yield. The production system that involved yearly rotation of corn and soybean, regardless of tillage system and nematicide seed treatment, exhibited the greatest yield potential during the 3 yr of this study. Such rotation system using NT can be an attractive option for farmers in this region, since NT has reduced field operations and labor requirements. University of Wisconsin–Madison, Agronomy Dep., 1575 Linden Dr., Madison, WI 53706. Received 22 Sept. 2016. Accepted 26 Jan. 2017. *Corresponding author ([email protected]). Assigned to Associate Editor Jeffrey Coulter. Abbreviations: 1C, first year of corn after 5 yr of soybean; 1S, first year of soybean after 5 yr of corn; 2C, second year of corn after 5 yr of soybean; 2S, second year of soybean after 5 yr of corn; 3C, third year of corn after 5 yr of soybean; 3S, third year of soybean after 5 yr of corn; 4C, fourth year of corn after 5 yr of soybean; 4S, fourth year of soybean after 5 yr of corn; 5C, fifth year of corn after 5 yr of soybean; 5S, fifth year of soybean after 5 yr of corn; AV, seed treatment containing abamectin; BF, seed treatment containing Bacillus firmus; CC, continuous corn; CS, corn–soybean rotation; NT, no-till; PN, seed treatment containing Pasteuria nishizawae; SCN, soybean cyst nematode; SS, continuous soybean. Published in Crop Sci. 57:1–9 (2017). doi: 10.2135/cropsci2016.09.0792 © Crop Science Society of America | 5585 Guilford Rd., Madison, WI 53711 USA All rights reserved. Published April 13, 2017