The Effects Of Row Spacing And Seeding Rates On Corn Yield Potential - Iowa

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 DEKALB® corn brand blends of 110 to 114 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

  • Across all corn products, spraying fungicide offered a 13 bu/ac advantage vs the unsprayed treatment. For this study, a 6.8 bu/ac response was considered a profitable response ($24/ac cost for fungicide application with $3.50 corn).
  • Fungicide use also increased plant health, as the average staygreen/intactness rating for the unsprayed products improved from 5 to 3 and 6 to 2 (respectively) when both compared to the products sprayed with fungicide.
  • Fungicide application had a minimal effect on grain moisture, with a 0.6% difference in moisture between the sprayed and unsprayed.