Courtesy of Jeff Bunting (GrowMark)

The above chart shows 2005 soybean yield data from the Central Illinois Region (Peoria, Springfield, Bloomington, and Champaign areas).  You should note that the greatest probability of maximizing soybean yield is achieved by selecting maturity groups from the 3.3 to 3.9 range for this geographic area. 

Since 2005 had a dry mid-season, there was some speculation that in a more normal year earlier maturing varieties would fare better.  However, a preliminary evaluation of data from previous years suggests that the a wetter season may only move the optimal maturity group to between the 3.2 to 3.8 range. 

We suggest you carefully consider these optimal values when selecting your soybean maturity groups.

D Pike