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.

• 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).

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).

• 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.