Planting Date, Rate, and Twin‐Row vs. Single‐Row Soybean in the Mid‐South

Comparisons were made of single‐row vs. twin‐row soybean [ Glycine max (L.) Merr.] production on a Beulah fine sandy loam (coarse‐loamy, mixed, active, thermic Typic Dystrudepts) (BFSL) and Sharkey clay (very‐fine, smectitic, thermic Chromic Epiaquerts) (SC) in 2009 and 2010 at Stoneville, MS. Seeding rates of 20, 30, 40, and 50 seed m −2 were planted on beds in 102 cm single rows or 25 cm twin rows with 102 cm centers. Three planting dates, mid‐April and mid‐May representing the Early Soybean Production System (ESPS) and mid‐June common to double‐crop soybean were made. Data included plants at growth stage R4 (full pod), nodes and pods plant −1 , yield, seed weight, and seeds m −2 . Twin rows yielded more than single rows on both soils (3.8 Mg ha −1 vs. 3.6 Mg ha −1 on BFSL; 4.2 Mg ha −1 vs. 4.0 Mg ha −1 on SC). Yields in 2010 were less than 2009 due to drought and heat stress. Delayed planting across row types decreased yields as much as 40% while increasing seeding rates had no effect. Twin rows produced more plants m −2 than single rows. Differences in nodes plant −1 were noted but did not affect yield. Pods per plant did not differ between row configurations on either soil. Seeding rates above 30 seeds m −2 did not produce greater yields and above 50 seeds m −2 on the BFSL produced seed with less weight. Twin–rows generally produced more seeds per m 2 than single rows. Small yield increases and high equipment costs make considering a twin‐row planter's usefulness with other crops important before purchasing it for soybean production.