Studies have found that planting soybeans earlier and using a higher population are the most effective methods for increasing yield.¹
This research is ongoing, but with most of the Midwest experiencing earlier last spring freeze dates overall, soybean planting dates keep trending earlier and earlier.
These changes in spring conditions are reflected in crop insurance dates with USDA Risk Management Agency revising early planting crop insurance dates for soybean before the 2023 season. This revision allows soybean in southern Ohio, Indiana, Illinois, and Iowa to be planted as early as April 5 and still receive insurance coverage. In the northern areas of these states, soybeans can be planted 10 days earlier than prior years (April 15) and still be covered.²
Aim to plant on or after the earliest planting date established by the RMA. Ultimately, both corn and soybeans have the highest yield potential when planted before May 20 in the Midwest³, so if all acres can be planted before May 20, it does not really matter whether soybean or corn is planted first.
However, after May 20, yield losses for late planting are greater for corn than they are for soybean, so if there is potential to plant after May 20, planting corn early should be your priority.
Main benefits of early soybean planting
- Better use of available sunlight: Early soybean planting typically produces a larger crop canopy earlier in the growing season, allowing plants to gather more sunlight during growth stages crucial for yield formation.
- Reduced moisture evaporation: The larger crop canopy also reduces soil moisture loss due to evaporation.
- Lengthened growth period and more pods per plant: The earlier soybeans are planted, the longer the period of vegetative growth, increasing nutrient and photosynthate accumulation, processes critical for pod and seed formation. This enables the crop to flower earlier and produce more vegetative nodes, increasing the potential for more pods per plant.⁴ To mitigate potential risks associated with early planting, check out Part 2: How to Reduce Risks of Planting Soybeans Early.”
- Improved soybean weed control: Early canopy development improves soybean’s competitive ability against weeds, limiting growth of early emerging weeds that could otherwise overtake a less mature crop.
What soybean varieties work best for early planting?
Greater soybean yields typically occur when early soybean planting is paired with very full-season varieties (+0.5 maturity group (MG)). To achieve this yield boost, your soybeans must be planted by the first week of May. Any yield advantage of longer-than-adapted varieties is lost if you plant in mid-May or after.
While long-season varieties have greater yield potential, they also can have a greater yield penalty if planted late. A long season variety planted late must also safely reach maturity before the first killing for the area or risk a large yield loss. When planted early, long-season varieties win the overall yield battle compared to shorter-season varieties (-0.5 MG). However, mid- to late-May planting dates produce yields similar for both long- and short-season varieties.⁵
Planting the latest-maturing variety adapted for your region is also key to preventing early-planted soybeans from maturing too quickly in the fall. If the crop is already past the R6 growth stage when late-season rain hits, the rain will not contribute to the yield increase that it would for soybean plants in earlier growth stages. Late-maturing varieties also help extend the reproductive period of the crop; if early-planted soybeans encounter unseasonably warm weather after planting, plants can emerge and flower significantly earlier than usual, which will negatively impact overall yield.
Because the environment changes from year to year, look for yield stability across multiple locations and several years. Varieties that consistently top the charts in yield for most locations and growing seasons typically have the best likelihood of high yields going forward.
Experts are available to help you make your decisions. Reach out to your seed retailer, a nearby extension office agent, or a seed company professional like your regional BASF representative.
________________________________________________
Endnotes
- Tesch, Kennedy. “New Research Suggests Planting Soybeans Before Corn to Maximize Soybean Yield.” Agweek, 23 Jan. 2024, www.agweek.com/crops/soybeans/new-research-suggests-planting-soybeans-before-corn-to-maximize-soybean-yield. Accessed 21 Dec. 2024.
- Kannberg, Seth. “Effect of ultra-early, early, and normal soybean planting dates and rye cover crop on soybean grain yield.” Agronomy Journal, 29 Feb. 2024, acsess.onlinelibrary.wiley.com/doi/10.1002/agj2.21550. Accessed 30 Jan. 2025.
- Licht, Mark. “Early Soybean Planting Considerations.” Integrated Crop Management, 15 Feb. 2024, crops.extension.iastate.edu/blog/mark-licht/early-soybean-planting-considerations. Accessed 21 Dec. 2024.
- Staton, Michael. “Planting Soybeans Early Offers Many Benefits.” MSU Extension, 18 Mar. 2011, www.canr.msu.edu/news/planting_soybeans_early_offers_many_benefits. Accessed 21 Dec. 2024.
- Naeve, Seth. “When and How to Plant Soybean.” Extension at the University of Minnesota, 2018, extension.umn.edu/soybean-planting/when-and-how-plant-soybean. Accessed 21 Dec. 2024.
