Research leads to potential increases in soybean yields

Missouri soybean yields have the potential to reach or exceed national averages, says University of Missouri Extension state soybean specialist Andre Reis.

Nationally, soybean yields have grown at a pace of 0.4 bushel per acre per year over the past 80 years, according to the USDA National Agricultural Statistics Service. Illinois growers saw a 0.47 bushel per acre per yield upturn, while Iowa boasted a 0.48 bushel per acre per year increase.

By contrast, Missouri yields fell behind, with an average increase of only 0.375 bushel per acre per year. Reis hopes to change that by providing growers with science-based research from MU to boost yields and farm income of soybean — the state’s No. 1 crop in acres and value, according to university news release.

Soybean production in Missouri is divided regionally into seven districts. Of those, yields in Districts 6 and 7, which comprise counties that run from the St. Louis area to the Missouri Bootheel, rose above the rest of the state. District 7 jumped to a 0.62 bushel per acre increase in 2020.

Several factors may play a part in areas where yields increased significantly, says Reis. Some farmers may adopt new technologies and strategies quicker than others. Reis says an example of this is adopting optimal planting dates, adjusting plant population according to variety requirements and enhancing soil fertility and crop protection management. In nonirrigated areas, strategies to avoid drought include combining maturity groups and planting dates to decouple pod setting and seed-filling periods from the hottest and driest periods of the season.

Reis’ work confirms previous MU research showing that planting date is one of the best predictors of yield. MU soybean variety testing data from past years shows an average loss of 3.5 bushels per week when planted after May 15.

Weather during soybean’s reproductive stages in July remains the biggest variable influencing yield. Soybean’s long flowering period allows it to withstand some extremes, but extended precipitation shortfalls and high temperatures hinder growth during this critical stage.

Reis has analyzed years of data from the MU Variety Testing Program and found that certain maturity groups produced significantly higher yields than others in all environments. Maturity Group IV plantings saw a yield increase of only 0.29 bushel per acre per year, while Maturity Groups II and III saw upturns of 0.34 bushel per acre.