The Effects of Row Spacing and Plant Population on Corn Yield Potential - DEKALB® - Iowa

Trial Overview

  • This trial was designed to provide customers in southern Iowa helpful row width comparison information, which is often limited for this region.

Research Objective

  • To compare corn yield potential in 20- and 30-inch row width systems on later maturity corn products in Iowa.
  • To help determine the yield response of higher populations within each row width system.
Soil Type
Previous Crop
Tillage Type
Planting Date
Harvest Date
Potential Yield
Planting Rate
Victor, IA
silty clay loam
33K, 38K, 43K

Site Notes:

Six DEKALB® brand corn products of 110 to 114 relative maturity were planted in two adjacent blocks at two different row spacings and at three different planting populations 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/acreA variable row spacing Case IH® 1215 Early Riser® planter unit was used for all plantings at general planting depth settings.Both blocks received 145 lbs/acre of anhydrous ammonia in the spring. Cultural practices were identical.Plots were 200 feet long with 2 replications at one location.



Understanding the Results

Table 1. Yields of DEKALB® Corn Brand Blends at each row spacing and planting population.
  • For the 20-inch row spacing, the planting population of 38K seeds/acre produced higher yields on average across products tested in 2017.
  • For the 30-inch row spacing, planting populations of 38K or 43K seeds/acre produced higher yields.
  • With current seed and grain prices, the rule of thumb is that a 1.5 bu/acre yield increase should pay for around 1,000 additional planted seeds/acre.

What Does This Mean for Your Farm

  • Corn products vary in yield performance at different populations and environmental factors. Consult the local seed guide for recommended product planting rates.
  • This study represents a single-site, twice-replicated demonstration.