Growers should take extraordinary precautions this year to check combine settings throughout the harvest day especially if they switch soybean maturity groups. Much of the rainfall that occurred in the dry areas of WI occurred too late to aid early maturity group soybeans (these soybeans were physiologically mature-R7 growth stage prior to rain); however many late maturity group varieties were still in the R6 (grain-fill) growth stage and may have benefited from the late August/early September rainfall. As growers proceed in harvest a quick in-field estimate can be preformed to assess where yield losses are occurring. The three areas of concern are pre-harvest loss (standing soybean), header loss (harvested swath in front of combine), and machine loss (harvested swath behind combine) (Images 1). In each area of interest count the number of beans per 10 ft2. Remember 40 seeds per 10 ft2 equal ~1 bushel per acre yield loss (Image 2).
For more information please see the following article.
Image 1. Fall volunteer soybean in winter wheat caused by machine loss.
Image 2. Two bushel per acre yield loss 
