The Effect of Seeding Rate and Planting Date on Irrigated XtendFlex® Soybeans

The Effect of Seeding Rate and Planting Date on Irrigated XtendFlex® Soybeans - 2021


  • XtendFlex® Soybeans are a new technology that was recently released for producers. Given that this technology has only undergone one growing season as a commercial product, various questions have arisen about product vigor under different agronomic practices and weather conditions. 

  • The objective of this study was to determine the effect of planting date and seeding rate on three XtendFlex® Soybean products.



LocationGothenburg, NE   
Soil Type Hord silt loam  


Planting DateSee below  
Harvest DateSee below 

Potential Yield
Seeding Rate
See below



  • The trial was arranged as a randomized split-split plot design with planting date as the whole plot, seeding rate as a sub plot, and soybean product as the sub-sub plot.
  • Planting Dates
    • 4/5/2021, 4/19/2021, 5/1/2021, 6/7/2021, and 6/21/21
  • Seeding Rates
    • 40,000, 80,000, 120,000, 160,000, 200,000, and 240,000
  • Soybean Products
    • 2.5 Maturity Group (MG) XtendFlex® Soybean product
    • 2.7 MG XtendFlex® Soybean product
    • 2.9 MG XtendFlex® Soybean product
  • Soybeans were irrigated throughout the growing season.
  • 60 lb phosphorus (P)/acre, 25 lb sulfur (S)/acre, 0.25 lb zinc (Zn)/acre were applied through strip-tillage application prior to planting.
  • Weeds were controlled uniformly across the study. 
  • Harvest Dates
    • 9/27/2021, 9/28/2021, 9/29/2021, 10/10/2021, and 10/16/2021


Planting date (results averaged by soybean product over all seeding rates)

  • The highest soybean yields were consistently observed with early planting dates (especially in April and May) (Figure 1).

  • The longer maturity group (MG) products (2.7 and 2.9 MG) had higher yields on April 5 and April 19 planting dates compared to the shorter MG soybean product (2.5 MG) (Figure 1). 

  • There was no difference in yield between the 2.7 and 2.9 MG products regardless of planting date (Figure 1).

  • The June 21 planting date had a negative impact on yield on all soybean products (Figure 1).

image Average soybean yields as impacted by planting date and soybean product at the Bayer Water Utilization Learning Center, Gothenburg, NE (2021).

Seeding rate (results averaged over planting dates) 

  • Soybean seeded at 40,000 seeds/acre had the lowest yields across all soybean products (Figure 2). 

  • The 2.5 MG soybean product had similar yields within the range of 80,000 to 240,000 seeds/acre (Figure 2).

  • The 2.7 MG soybean product average yield increased steadily within the 80,000 to 200,000 seeds/acre range and then declined significantly at the higher seeding rate of 240,000 seeds/acre (Figure 2).

  • No difference in yield was observed from 80,000 to 200,000 seeds/acre for the 2.9 MG soybean product. The highest average yield was obtained with the 240,000 seeds/acre rate (Figure 2).

image Average soybean yields as impacted by seeding rate and soybean product at the Bayer Water Utilization Learning Center, Gothenburg, NE (2021).


  • For this study, plots planted at the earlier planting dates had higher yields across all soybean products, especially in the 2.7 and 2.9 MG. Late planting (June 21) had a negative impact on yield regardless soybean maturity group.

  • Depending on soybean product, irrigated XtendFlex® Soybeans planted in the range of 160,000 to 240,000 seeds/acre helped maximize yield potential.  

  • Farmers should work with their local seeds sales team member to help identify the best adapted XtendFlex® Soybean product for their production systems.

Impact of Seeding Rate on Irrigated XtendFlex Soybeans - 2020


  • XtendFlex® soybeans is a new trait platform available for farmers to plant in the spring of 2021.  

  • The objective of this trial was to help answer questions regarding the impact of planting rate on three XtendFlex soybean products across two planting dates.  



LocationGothenburg, NE   
Soil Type Hord silt loam  


Strip till

Planting Date5/20/20 & 6/12/20  
Harvest Date10/2/20 & 10/9/20 

Potential Yield
Seeding Rate
40K, 80K, 120K,
160K, 200K, 240K


  • This trial was a split plot design with planting date as the whole plot, seeding rate as the sub plot, and soybean product as the sub-sub plot.  
  • Planting dates:  
    • May 20, 2020
    • June 12, 2020

  • Seeding rates: 
    • 40,000 seeds/acre
    • 80,000 seeds/acre
    • 120,000 seeds/acre
    • 160,000 seeds/acre
    • 200,000 seeds/acre
    • 240,000 seeds/acre
  • Soybean products, by maturity group (MG):
    • 2.3 
    • 2.5
    • 2.7

  • Trial was sprinkler irrigated.
  • Nutrient application included 27.5 lb N/acre, 15 lb S/acre, and 70 lb P/acre strip-till applied prior to planting. 
  • Weeds were controlled as needed and no additional fungicide or insecticides were used.
  • The May 20 planting date was harvested on October 2 and the June 12 planting date was harvested on October 9. Total weight, test weight, and moisture content were collected to calculate yield per acre.


image Figure 1. Average yield of three XtendFlex® soybean products planted at two planting dates (May 20 and June 12) as influenced by seeding rate.
  • There was no significant interaction between seeding rate, soybean product, and planting date. 

  • The impact of seeding rate followed the trend of previous research where average soybean yields steadily increased from 40K to 120K seeds/acre and then leveled off (Figure 1). 

  • The 160K seeds/acre rate had the highest average yield with no increase in yield observed with the 200K or 240K seeds/acre rates (Figure 1).   

  • The 2.3 MG soybean product had the highest average yield at 75.5 bu/acre while the 2.5 MG and 2.7 MG products yielded 72.1 and 74.4 bu/acre, respectively with an LSD (0.1) of 1.1.  

  • No difference in yield was observed from planting date with each date having an average yield of 74 bu/acre. 

image Figure 2. Representation of the planting date, soybean product, and seeding rates in August of 2020.


  • At this location, XtendFlex® soybeans planted around 160K seeds/acre helped maximize yield potential.

  • Farmers should work with their local seeds sales team member to help identify the best adapted XtendFlex® soybean product for their production system.



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