Soybean Replant Decisions

Decisions to replant reduced soybean stands can be difficult to make. It is important to understand the cause of an inadequate stand to help prevent a reoccurrence of the problem.¹ A stand count and assessment of plant loss should be made. When deciding, consider crop insurance, time in the growing season, and the costs associated with replanting such as seed, fuel, labor, and other inputs.

Evaluating the Existing Stand

Factors that can contribute to less-than-ideal soybean stands include: planting into a poor seedbed, planter adjustment problems, poor quality seed, soil crusting, inadequate or excessive soil moisture, seedling diseases, or other environmental issues. Understanding the cause of an inadequate soybean stand is important to help prevent a reoccurrence of the problem if the decision is made to replant. Spotty stand reductions throughout a field can be caused by poorly drained areas, sandy soil patches with inadequate soil moisture, or even soil compaction in certain areas. Before deciding to replant, evaluate the stand for population and uniformity, and estimate the yield potential of the existing stand. When evaluating soybean stands, only count plants that have a good chance of survival. Soybean plants cut off below the cotyledon by hail or other means have no potential for regrowth. However, soybeans can recover from moderate leaf tissue damage with minimal effect on yield potential.^1,2

To evaluate the plant population for 30-inch rows, count the number of plants in 17 feet 5 inches of row and multiply the number of plants by 1,000 to determine plants per acre. For 15-inch rows, count the number of plants in 34 feet 10 inches of row and multiply by 1,000. Repeat these counts in several locations in the field.

Another method for evaluating soybean stands in any row spacing, especially drilled, is to use the hoop method. Measure the diameter of a hoop, toss it into the field, and count the number of plants inside the hoop. Do this in at least five to 10 locations in the field. Multiply the average number of plants by the appropriate factor listed in Table 1 to determine the number of plants per acre. Notice that a hoop diameter of 28 ¼ inches allows you to simply multiply by 10,000 to estimate the number of plants per acre. This hoop size can be made by cutting tubing to 88 ¾ inches in length and joining the ends to form a circle.

Table 1. Stand count evaluation factors, by hoop diameter, to determine soybean plant population using the hoop method.

Evaluating and Managing the Yield Potential of the Existing Stand

Many studies have examined the yield potential of soybean stands. What may appear to be a substantial stand reduction does not necessarily translate into a substantial loss of yield potential. Soybean plants can compensate well for gaps in the field. Gaps less than two feet in diameter can be filled in by branches from adjacent soybean plants. A University of Illinois study found that established plant stands of eight, six, and four plants per foot of row in 30-inch rows (equals approximately 140,000; 105,000; and 70,000 plants per acre, respectively) differed in yield potential by only 5%. Final soybean plant stands of 73,000 plants/acre or more consistently yielded 90% or more of maximum yield potential. A 50% stand loss resulted in only a 16% loss in yield in areas of the field in which there were eight plants per foot of row in row sections with no skips or gaps. A 50% stand reduction with four plants per foot of row resulted in a 22% loss of yield potential. Assuming an original yield potential of 60 bu/acre, a field with a 50% loss of stand with four plants per foot of row could still yield 47 bu/acre.²

A 2024 study conducted at the Bayer Crop Science Water Utilization Learning Center at Gothenburg, NE examined the effects of planting date, seeding rate, and seed treatment on soybean yield. Planting dates ranged from March 18 to June 25 at approximately two-week intervals. No significant yield difference was found comparing treated seed planted at 80,000 seeds/acre vs 140,000 seeds/acre, across all planting dates. For plots that were seeded at 140,000 seeds/acre (treated seed), final stands ranged from about 92,000 plants/acre to 117,000 plants/acre when planted from March 18 through May 13, with yields consistently in the range of 70 to 74 bu/acre. For planting dates of May 27, June 10, and June 25, yields declined significantly to 66, 55, and 53 bu/acre, respectively, despite having the highest final stands of about 120,000 plants/acre. In this trial, planting date had a greater effect on final yield than either seeding rate or final stand, with later planting dates producing significantly lower yields even with high stand numbers. The effect of a later planting date should be considered when deciding whether to replant.

Reduced soybean stands can increase light penetration to the soil surface. This can increase the potential for weed seed germination and weed competition, and increase soil water evaporation and soil temperature. These factors can affect nodulation, biological nitrogen fixation, and nutrient and water availability. Make weed control a high priority, especially in fields with reduced stands, in order to help maximize the yield potential of the existing crop.

Deciding Whether to Replant

• Determine what caused the stand loss and evaluate the population and uniformity of the remaining stand. To determine stand levels, wait several days after soybean emergence or after damage (hail, chemicals, etc.) and only count live plants that will continue to develop and contribute to yield production.
• Estimate the yield potential of the existing stand. The yield of early planted soybean is usually maximized with stands ranging from 100,000 to 135,000 plants/acre. Stands as low as 50,000 plants/acre have been found to have only about a two bu/acre yield loss compared to the optimum stand density.³
• Consider the calendar date and the effect of delayed planting. Research by the University of Nebraska found that when planting dates ranged from April 23 to June 19, the average yield penalty was as high as 0.25 bu/acre per day compared to the highest yield which was obtained from the April planting.⁴
• Determine the full cost of replanting, using the estimated yield potential if the crop is replanted as well as any insurance availability.
• Evaluate the current and forecasted weather conditions and consider how the date of replanting can affect yield potential.
• Determine if recent applications of residual herbicides could prevent replanting. Make sure that you follow replant instructions on the herbicide label.
• Replanting into the existing stand is not recommended because this can result in nonuniform plant sizes causing uneven competition for resources. If young stands contain large areas of damaged plants, replanting only into those areas could be an option. Research suggests that tillage to destroy the existing stand followed by replanting may be the least productive replant option for soybean, compared to leaving a stand with adequate population and distribution.
• If a decision is made to replant, use the same soybean variety with the same traits you originally planted. Changing to an earlier maturing variety may not be necessary depending upon the replant date.
• If replanting, consider using slightly higher seeding rates. This may help increase the soybean plant growth efficiency, reduce weed competition, and potentially help produce more pods per acre.
• Scout areas of different planting dates in the same field for late-season pest problems. The difference in planting date may cause a pest to be in one part of the field but not in another.⁵

Please consult with your local retailer or seed representative to learn more about issues and options related to soybean replants.

Sources

¹Robinson, A. and Conley, S. 2007. Thin soybean stands: Should I replant, fill in, or leave them alone? Purdue University Extension. SPS-104-W. https://www.extension.purdue.edu/extmedia/sps/sps-104-w.pdf

²Whigham, K., Farnham, D., Lundvall, J., and Tranel, D. 2000. Soybean replant decisions. (E. Edwards, Ed.; M. Sailer, Des.). Iowa State University Extension. PM1851. https://store.extension.iastate.edu/product/5422

³2024. Soybean replant decisions made easy(ish)! Coolbean Blog. https://coolbean.info/2024/05/09/soybean-replant-decisions-made-easy/

⁴Specht, J., Grassini, P., Brhel, J., Mueller, N., Elmore, R., and Edreira, J.I.R. 2018. Amplifying positive impacts of early soybean planting. University of Nebraska–Lincoln, Cropwatch. https://cropwatch.unl.edu/2018/amplifying-positive-impacts-early-soybean-planting/

⁵Brhel, J., Specht, J., Elmore, R., Nygren, A., and Mueller, N. 2020. Soybean replanting considerations. University of Nebraska–Lincoln, CropWatch. https://cropwatch.unl.edu/2020/soybean-replanting-considerations/

⁶2023. Corn & soybean field guide 2023 edition. Purdue University Extension. ID-179.

Web sources verified 04/16/2025. 1314_108551