Soybean Seeding Rate by Planting Date

• Previous work at the Bayer Learning Center at Monmouth, IL has shown that planting date is an important factor affecting soybean yield potential.

• In most years, an earlier planting date could be a low-risk/high-return soybean management practice.

• A generally recommended practice is to increase soybean seeding rates when planting occurs later in the season^.1,2 

• In 2019, the Bayer Learning Center at Monmouth, IL conducted a trial to determine if seeding rate influences the average yield of soybean across multiple planting dates.  

   

• Two Roundup Ready 2 Xtend® soybean products with relative maturities (RM) of 3.4 and 3.6 were planted on two planting dates at four different seeding rates.

• The planting dates were:
  • 4/24/19 (early)
  • 6/3/19 (late)
• The seeding rates/acre were:
  • 40,000 
  • 80,000 
  • 120,000  
  • 160,000 

• There were two replications for each treatment.  

• Plots were kept weed-free.

• The soybean plant is rather versatile in its growth and development. As plant population decreases, the plants tend to branch and develop additional nodes to attempt to compensate (Figure 1).

• The yields of the two soybean products for each planting date were averaged together because the yields of each were very similar. 

• In this trial, the April 24 planting date favored lower seeding rates, while the June 3 planting date favored higher seeding rates.  

  • This response is in line with university recommendations.^1,2
  • However, the higher overall average yields for the June 3 planting date are not typical of previous Bayer Learning Center results.  Extreme weather conditions during the growing season may have contributed to this result.

• Return over seed cost was maximized at the 80,000 seeds/acre rate for the April 24 planting date, while 120,000 seeds/acre provided the highest return for the June 3 planting date.

  • These calculations assumed a soybean price of $9.50/bu and a seed cost of $69 for a 140,000 unit of seed.

• These results suggest that:

  • Early planting of soybean may help maximize profitability. Early planting assumes that the soil and weather conditions are suitable for seedbed preparation and seed germination.
  • Late planting may require increased seeding rates to help optimize yield and profit potential.

• The optimum soybean seeding rate is highly variable from year to year.

Contact your local Field Sales Representative or Technical Agronomist for planting recommendations for the current situation and year. 

¹Staton, M. 2019. Late-planted soybean recommendations. Michigan State University Extension. https://www.canr.msu.edu/.

²Nafziger, E. 2019. Early-season soybean management for 2019. The Bulletin. University of Illinois. http://bulletin.ipm.illinois.edu/.

Web sources verified 10/29/19. 3011_R1