The most common planting configurations in North American soybean production are 15-inch and 30-inch rows, each accounting for more than 1/3 of total acreage.
Numerous research studies have been conducted to determine optimal soybean row spacing for maximum yield potential. In general, studies have found that soybean yield potential is often greater with row spacings narrower than 30 inches.
A review of soybean row spacing studies published in the last decade showed that 15-inch rows outyielded 30-inch rows by 4 bu/A on average. However, many of these studies used higher seeding rates with narrower row spacings, partially due to the use of less accurate drilled soybeans versus using a more accurate planter. A study conducted in 2008-09 (Cox and Cherney, 2011) found no row spacing by seeding rate interaction for soybeans planted in 7.5 inch, 15-inch and 30-inch rows.
“Other than yield, the most important factor driving soybean row spacing practices are equipment and time management during the planting season,” said Dr. Mark Jeschke, Pioneer Agronomy Manager. “One of the key issues growers must consider is whether the economics of their farm justify having a machine dedicated specifically to planting soybeans.”
The need for fungicide and/or insecticide applications may also impact row spacing decisions. When an application is made during vegetative growth, narrow-rowed plants are generally able to compensate for damage caused by the sprayer wheels with little reduction in yield. For applications made following the R1 growth stage, which would include most foliar fungicide and insecticide applications, wheel damaged areas will have lower yield. A research study in Delaware and Virginia found significant yield reductions due to sprayer wheel damage in R4 soybeans planted in 7.5-inch and 15-inch rows, while soybeans planted in 30-inch rows and wider did not sustain any wheel damage (Holshouser and Taylor, 2008).
Every field is unique and each grower should carefully consider the costs, risks and benefits of soybean row spacing options prior to making a decision.