2005 Year in Review

Soybean Row Width – The Debate Continues

Questions and discussion over soybean row width continue. In fact, that topic may always be debated. Eric Adee, research specialist at the Northwestern Illinois Agricultural Research and Demonstration Center near Monmouth, has just provided an update on the ongoing soybean row spacing study.

In 2004, drilled (7–inch row width) soybeans yielded more than 10 bushels per acre better than those planted in 15-or 30-inch row spacings. The study was planted no-till on April 28.

The seven-year average yield benefit for the drill was not as dramatic as that seen in 2004. Over the seven years of the study, the drill has averaged 0.7 bushel per acre better than 15-inch rows and 3.6 bushels per acre more than 30-inch rows. This data is consistent with similar row spacing studies conducted at other University of Illinois agronomy research centers.

Adee notes that yield is related to how early the soybean canopy closes, intercepting available sunlight. Additional factors such as pests and lack of rainfall can affect the relationship between canopy and yield, but Adee indicated none of these factors had a major impact in the study.

The advantage for the drilled 7-inch rows in 2004 may have been more pronounced because the relative cool temperatures and fewer sunny days were more yield limiting than usual. Under these conditions, any differences in light interception capabilities could have been magnified in the yield.

Adee concludes that it is best to use long-term averages when using this data to make soybean row width decisions. Adee can be contacted at the Ag Center by phoning 309-734-7459.

by  Editor, theCity1.com
January 10, 2005