Planting Soybean with a Grain Drill Inconsistently Increases Yield and Profit

Published in Agron. J. 104:1065–1073 (2012) Posted online 29 May 2012 doi:10.2134/agronj2012.0109 Copyright © 2012 by the American Society of Agronomy, 5585 Guilford Road, Madison, WI 53711. All rights reserved. No part of this periodical may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or any information storage and retrieval system, without permission in writing from the publisher. S production has increased steadily while wheat (Triticum aestivum L.) production has declined somewhat since 2000 in the northeastern United States (New York Agricultural Statistics Service, 2011). Nevertheless, grain drills are widely available on many farms in the northeastern United States. Consequently, most growers in this region have the option of using a grain drill to seed soybean in 0.19-m rows or a row crop planter to seed soybean in 0.38-m rows (with inter-units) or 0.76-m rows. The yield advantage of planting soybean in 0.19vs. 0.76-m rows is fairly consistent in northern latitudes but less consistent south of latitude 43°N (Lee, 2006). Also, planting soybean in 0.19 compared with 0.76-m rows results in less weed emergence after an initial herbicide application, which may eliminate the need for a sequential postemergence herbicide application and lower weed control costs (Bradley, 2006). Row crop planters compared with grain drills, however, provide more uniform seed depth and seed spacing resulting in improved emergence and more uniform plant establishment, which may allow for lower seeding rates and seed costs (Bertram and Pedersen, 2004). Furthermore, soybean in 0.19or 0.38-m rows compared with 0.76-m rows can incur significant wheel-traffic damage and yield reductions from the increasing use of postemergence fungicide applications during reproductive development (Holshouser and Taylor, 2008; Hanna et al., 2008). Consequently, planting soybean with a grain drill in 0.19-m rows or with a row crop planter in 0.38or 0.76-m rows can affect not only yield but also weed control costs, seed costs, and wheel-traffic damage to soybean. Northeast soybean producers can benefit greatly from farmerparticipatory studies with field-scale equipment that compare the agronomics and economics of planting soybean at recommended seeding rates with a grain drill in 0.19-m rows vs. a row crop planter in 0.38or 0.76-m rows. Lambert and LowenbergDeBoer (2003) summarized the results of numerous soybean row spacing studies in northern latitudes and reported a 4.8% yield advantage for drilled (<0.25) compared to 0.38-m rows and a 15.9% yield advantage compared to 0.76-m rows. Bertram and Pedersen (2004) reported that soybean planted in 0.19and 0.38-m rows yielded between 5 and 9.6% more than in 0.76-m rows in three regions of Wisconsin in a 3-yr study. Bertram and Pedersen (2004) also reported that soybean in 0.38-m rows yielded 4.8% more than in 0.19-m rows in southern Wisconsin, but the same in northern and central Wisconsin. Janovicek et al. (2006) found that soybean drilled in 0.19 m compared with 0.76-m rows yielded 13% more under moldboard plow and no-tillage systems in Ontario, Canada. In this same study, however, soybean in 0.19-m rows yielded 4% greater than soybean in 0.38-m rows under moldboard tillage and similarly under no-till conditions. Cox and Cherney (2011) reported that drilled soybean ABSTRACT Growers can plant soybean [Glycine max( L.) Merr.] with a grain drill or row crop planter, which can affect seed and weed control costs and yield. Farmers planted soybean with a drill in 0.19-m rows and row crop planter in 0.38and 0.76-m rows at two seeding rates (420,000 and 321,000 seeds ha–1) in two field-scale studies in New York to obtain agronomic information and conduct partial budget analyses to aid in future planter selection and purchase decisions. Soybean intercepted more light at flowering in 0.19 (65–70%) compared with 0.76-m rows (50–55%), despite lower early plant establishment (~70 and ~85%, respectively) at both locations. At a no-till location, 0.76-m rows compared with narrower rows had greater weed density at full pod stage (19.7 vs. 6.3 and 5.1 weeds m–2) and weed biomass at harvest (13.7 vs. 6.6 and 7.3 g m–2, respectively) but similar yield (~3.30 Mg ha–1). At a chisel tillage location, soybean in 0.19-m rows at the recommended 420,000 seeds ha–1 yielded 4% more (4.27 Mg ha–1) than in 0.76-m rows at the recommended 321,000 seeds ha–1 (4.11 Mg ha–1). Partial budget analyses indicated that soybean in 0.19-m rows at 420,000 seeds ha–1 had ~$30 ha–1 greater profit compared with 0.76-m rows at 321,000 seeds ha–1. Partial budget analyses indicated that at present prices the 4% yield advantage offset purchasing and owning costs of a new drill and added seed costs, if planting 250 and 500 ha of soybean.