Past research looking at intensifying soybean yields was specifically focused on a few treatments applied at early reproductive stage (R1-R3), but based on recent preliminary research, more attention needs to be invested into “late-season” (R4-R6 stages) management factors. Soybeans accumulate between 30-50% of the final yield during the seed filling period (R5-R7 stages) and thus more emphasis on potential factors enhancing seed filling via “late-season” management practices should be evaluated to capture further yield improvements on this crop at the field scale. Relative to the final total yield (biomass) at harvest, soybeans only accumulate 60% until R5 stage, with the other 40% accumulated during the seed filling (R5-R7), lasting 30-40 days.
Still, the main question is “What can be the potential impact of improving yields by enhancing seed filling?” To answer that question we are presenting an example with data collected from Rossville during the 2017 growing season. The information shows the rate of dry matter accumulation on soybean seeds from the R5 to R7 stages, portraying the total number of days (37 days) for an overall soybean yield of 61 bu/acre. In this example, improving “green leaf area” duration and extending the seed filling period by only 7 days provided a yield benefit of more than 10 bu/acre. Yield level was approximately 50 bu/acre with a 30-days seed filling duration to more than 60 bu/acre when the duration was prolonged to a total of 37 days of R5-R7 (increasing nearly 1.5 bu for each additional day in seed filling). Therefore, management practices that can contribute to extend the seed-filling period (at least for a few days) impacting soybean yields across different production environments should be further investigated.