From Seeds for Success, Agronomy Update - April 2015
Planting soybeans for maximum yield means planting earlier versus later. University of Illinois research includes 2014 planting date trial data from central and northern Illinois. It shows declining yields with later planting, and losses of more than a half bushel per day of delay.
Soybeans planted April 23rd yielded 95 bushels per acre. Yields on soybeans planted June 15 were 66 bushels per acre.
Regarding varietal differences, research shows there seems to some advantage in choosing to plant fuller-season varieties earlier rather than later, though that strategy tends to work against the goal of using different maturities to spread harvest.
AgVenture’s Jeff Shaner reminds growers, “Earlier planted soybeans maximize the leaf canopy’s ability make the most of photosynthesizing sunlight during the longest days of summer.”