Non-B.t. Refuge Corn Hybrids: Seeding Rate Response – South

January 13, 2026

TRIAL OBJECTIVE

  • Corn product seeding rate is one of the most important decisions made when planting corn and can only be made prior to or during planting.
  • Planting non-Bacillius thuringiensis (B.t.) technology/refuge corn products is essential for compliance with refuge management plans and to help ensure the viability of B.t. technology across the corn/cotton ecosystem.
  • For this reason, the Bayer Crop Science Learning Center at Scott, MS evaluates seeding rates each season for DEKALB® brand, non-B.t. corn products.
  • Several primary questions are asked including
    • If I plant more seed, do I reach greater yield potentials?
    • If I plant more seed, does the crop suffer in standability (i.e. does lodging occur)?
    • Would an increase in seeding rate provide a return on seed investment?

RESEARCH SITE DETAILS

Research Site Details


Table 1. DEKALB® brand corn products, traits, and maturities planted in the trial.

Table shows DEKALB® Brand Hybrid Corn Seed, relative maturities, and their herbicide resistant corn trait which is Roundup Ready® Corn 2.
  • Management Plans
    • All field work, tillage and herbicides were per local standards.
    • Seeding rates (seeds/acre)
      • 32,000
      • 36,000
      • 40,000
  • The trial used non-replicated strip plots
    • Field yield data was collected using a commercial combine via whole plot harvest and corrected to 15.5% moisture content.
  • Plot Size
    • 12 rows – about 0.50 acre/plot
  • Return on Investment (ROI) Calculations
    • Elevator grain price of $4.02/bushel (cash price on 09/01/2025 at Scott, MS).
    • Seed cost of $370.00/80,000 seed count bag or $4.63/1,000 seeds planted.

UNDERSTANDING THE RESULTS

Return on investment for planting 8 DEKALB® Seed Roundup Ready® Corn 2 Hybrids.
Figure 1. Return on investment ($/acre) comparison between seeding rates of 32,000, 36,000, and 40,000 seeds/acre for eight DEKALB® brand Roundup Ready® Corn 2 products.

  • In this trial, five of the eight corn products had a net return greater than $10.00/acre (accounting for seed/grain price) for increasing the planting rate from 32,000 to 36,000 seeds/acre (Figure 1).
  • This data is similar to previous years data in that, DEKALB® brand Roundup Ready® Corn 2 products respond positively to planting rates in the 32,000 to 36,000 seeds/acre range (Figure 2). Each product is unique, and growers should evaluate them carefully for positioning on their operation.

Corn yield response table for planting 8 DEKALB Seed Roundup Ready® Corn 2 Hybrids at three seeding rates.
Figure 2. Average yield response of eight DEKALB® brand Roundup Ready® Corn 2 products to seeding rates of 32,000, 36,000, and 40,000 seeds/acre.


KEY LEARNINGS

  • No lodging was visually observed at any final population in this trial (data not shown).
  • Growers should study and understand the recommended seeding rates for corn products they choose to plant, regardless of technology. Determining the best seeding rate for field conditions is an initial step toward maximizing corn product yield potential.
  • Please contact your local DEKALB® brand representative for more information.

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