​The Effects of Row Spacing and Seeding Rate on Corn Yield Potential

Trial Objective:

  • This trial was designed to provide farmers in southern Iowa helpful row width comparisons (20- and 30-inch row width systems) on later maturity corn products in Iowa and to help determine the yield response of higher seeding rates within each row width system.

Research Site Details

  •  Five Channel® corn brand blends of 109 to 116 relative maturity were planted in two adjacent blocks, at two different row spacings, and at three different seeding rates within each row spacing:
    • — 6-row, 30-inch row spacing planted at 33,000 (33K), 38,000 (38K), and 43,000 (43K) seeds/acre
    • — 12-row, 20-inch row spacing planted at 33K, 38K, and 43K seeds/acre
  • A variable row spacing Case IH® 1215 Early Riser® planter unit was used for all plantings at general planting depth settings.
  • Both blocks received 150 lb/acre of anhydrous ammonia in the spring. Cultural practices were identical.
  • Individual plots were approximately 200 feet long.

Understanding the Results

  • Differences in yield potential between the 20- and 30-inch systems can vary from year to year based upon environmental conditions (heat units, moisture, disease, etc.).
  • In 2018, yield levels were significantly lower in 20-inch rows at this location but close to parity in 2017.
  • Independent of the row spacing system, products need an adequate seeding rate to realize full yield potential and return on investment.
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