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 rowwidth 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 Kruger™ Seeds corn brand blends of 108 to 115 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.