When--Or Should--You Replant Soybeans?
The title of this article poses a question that has no concrete answer. And here is why. Soybeans can compensate for a population that is much lower than intended or planned for because of their ability to compensate. The following two articles shed come light on this phenomenon.
An article titled Soybean overcome differences in row spacing and seeding rate to maintain stable yield by Seraglio et al. summarizes results from 7 years [2016-2023] of research that was conducted in Iowa on two sites, both with silty clay loam soil texture. The following are major points from this article.
• Planting rates of 90 to180 thousand seeds/acre were used.
• Seeding rate significantly affected yield in 7 of the 14 site-years, but differences among the seeding rates used in this study were inconsistent and small, and exceeded 3.5% in only 1 of 14 site-years.
• In the site-years that the seeding rate effect on yield was significant, the lowest seeding rate used in this study [90-120 thousand/acre] produced the statistically greatest yield one-half of the time.
• The authors concluded from these results that the small and usually insignificant seeding rate effect on soybean seed yield varies from year-to-year because soybean plants can use compensatory mechanisms such as branching to adapt to a varying number of plants in a given area.
• These results suggest that producers can plant fewer soybean seeds [<120 thousand/acre] to reduce input costs without sacrificing seed yield.
An article titled Low soybean plant population: Is replanting necessary? summarizes information provided by soybean agronomists that represent eight U.S. soybean-growing states, including two Midsouth states. Pertinent points from this article, along with recommendations from the specialists, follow.
• The content of this article is provided to give guidance on the agronomics that should be considered before replanting soybeans.
• Replanting soybeans will increase input costs and lose the potential yield advantage gained from the earlier planting that is to be replaced.
• Plants that have been cut off or irreparably damaged below the cotyledons will not recover.
• If a majority of plants in a field are broken, producers should determine if the break is above or below the cotyledonary leaves since plants that are irreparably broken below those leaves will die.
• The authors recommend repair planting, which is planting only affected areas of a field vs. destroying and replanting the stand in the whole field.
• Soybean producers should consider the quality of the remaining stand–i.e. is the remaining stand uniform, injury level of the remaining plants, condition of both the terminal growing points and axillary buds of the remaining plants, the growth stage of plants at time of damage–as well as the calendar date of replanting.
• Soybean farmers should consider replanting if there are fewer than 60,000 and 75,000 healthy, uniformly distributed plants/acre in fields in the southern and northern U.S. regions, respectively.
Soybean producers should keep the following points about replanting in mind.
• Can seed of the preferred variety be obtained for replanting?
• Will potential revenue from the replanted crop be sufficient to cover the cost of replanting and still result in a profit?
• Will replanting result in increased weed and pest control issues that will increase management costs?
• The decision to replant should be based on objective [planned sampling] vs. subjective reasoning.
• Click here to access an article that describes sampling methods that can be used to assess stand.
Composed by Larry G. Heatherly, May 2025, larryh91746@gmail.com