Research leads to potential increases in Missouri soybean yield

COLUMBIA, Mo. — 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.

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.

Even within the districts, some areas showed standout performances, including Atchison, Lafayette, Miller, St. Francois and Butler counties. Pockets of District 1 in northwestern Missouri also fared well above the statewide average.

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.

Overall, each of the seven districts saw the biggest yield jumps since the period of 1971-1996.

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. The variety testing program has collected data at Missouri test plots throughout the state since 1973. Researchers note crop management practices and soil and water conditions in the results.

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. See https://varietytesting.missouri.edu/soybean/ for more.

Reis developed a maturity group decision tree to help growers decide which maturity group to choose. The tree considers day length, seasonal potential evapotranspiration rate, preseason precipitation, precipitation during the early vegetative state, day length during flowering and other factors. The decision-making tool is available by request from Reis.

Illinois and Iowa soybean yields outpaced Missouri by 0.10 and 0.11 per acre during the same period. Kansas lagged slightly behind Missouri with 0.02 less bushels per acre.

For more information, contact Reis at areis@missouri.edu or call 573-882-4771

See interesting facts and figures on Missouri soybean at https://extension.missouri.edu/programs/soybean/soybean-facts-and-figures.