In the Mid-South, twin-row soybean production is becoming a popular growing technique for soybean producers. An estimated 80 percent of the total hectares grown in the Mississippi Delta are planted in this configuration.

While growers report this method increases seed yields, especially when used with specific cultivars planted in April or early May, there is no research data to support their claims.

Arnold Bruns, a U.S. Department of Agriculture (USDA) Agricultural Research Service (ARS) scientist, compared the effects of planting soybeans in twin-rows versus single rows.

The full results from his study are published in the September-October 2011 issue of Agronomy Journal.

Twin-rows yielded more than single-rows on both soils on which the experiment was conducted - a Beulah fine sandy loam and a Sharkey clay, common soils to the Mississippi Delta. The number of pods per plant did not differ between twin-rows and single-rows.

Drought and high temperatures likely reduced yields in 2010 compared to 2009. Delayed planting on both soil types resulted in decreased yields. Also, increasing seeding rates above 30 seeds-per-meter resulted in no yield increases.

"While twin-rows did result in higher seed yields, the increase was only worth about $75 per hectare," said Bruns. "It is necessary to consider a twin-row planter's usefulness in other crops such as corn and cotton before investing in it for soybean production."