Submitted to: Agronomy Journal
Publication Type: Peer reviewed journal
Publication Acceptance Date: 2/9/2011
Publication Date: 3/9/2011
Citation: Bruns, H.A. 2011. Comparisons of single-row and twin-row soybean production in the Mid South. Agronomy Journal. 103:702-708. Interpretive Summary: Twin-row soybean production is increasing in popularity in the Mid South with undocumented reports of increasing yields resulting from this type of planting. One cultivar each of a Maturity Group IV and MG V soybean were grown in both single-row and twin-row configurations at 20, 30, 40, and 50 seed per square meter seeding rates on an irrigated sandy loam and a clay soil common to the Mississippi Delta. Twin-rows, especially on the clay soil, yielded more seed than single-row plantings by producing more seed per plant. Only at the higher seed rates was this noticed on the sandy loam. Seeding rates, regardless of row type, or soil did not differ in seed yields. Row type and seeding rate also had no effect on seed weight or bulk density. The lack of consistent yield increases and the high cost of twin-row planters makes it necessary to consider the versatility of a twin-row planter with other crops before investing in one. Also, the lack of yield increases with seeding rates above 30 seed m-2 strongly suggest that seeding rates above this level are a waste of valuable seed.
Technical Abstract: A Maturity Group (MG) IV and MG V soybean [Glycine max (L.) Merr] cultivar were planted in single-rows and twin-rows on 102 cm beds at 20, 30, 40, and 50 seeds m-2 in a Beulah fine sandy loam (coarse-loamy, mixed thermic Typic Dystrochrepts) in 2008, 2009, 2010 and Sharkey clay (Vertic Haplaquept) in 2009 and 2010 at Stoneville, MS. The experimental design was a split-plot of a randomized complete block replicated four times. Despite furrow irrigation, drought and consistent maximum temperatures >32.0C during 2010 likely reduced established plants, yields, seed weight, and seed bulk density at both sites. Twin-rows produced more established plants than similar single-rows at both sites which helped increase yields with twin-rows compared to single-rows on the clay soil. Yields on the clay soil did not differ among seeding rates. Yields from twin-rows on the sandy loam were only greater than the single-rows at 40 and 50 seeds m-2 for the MG IV cultivar and did not differ for the MG V. The MG IV cultivar tended to yield better than the MG V at both sites. The MG IV cultivar had an average of 20 nodes plant-1 compared to 15 for the MG V. Both cultivars at the sandy loam site average 59 pods plant-1, while the MG V cultivar produced 70 pods plant-1 vs. 63 pods plant-1 for the MG IV cultivar on the clay. Twin-rows did not produce more pods plant-1. Row type or seeding rate had no effect on seed weight or seed bulk density at either site. Given the cost of twin row planters and the small increase in yields of twin rows the equipment’s versatility with other crops must be considered before making the transition to twin-rows. Also, seeding rates above 30 seed m-2 appears to be a waste of seed.