Based on his own experiences and those of other farmers, universities and seed companies who have made direct comparisons of 15- and 30-inch rows, Marion Calmer sees a half dozen major advantages to switching to ultra-narrow row corn:

• A 5- to 15-bushel-per-acre yield increase.
• More complete weed control.
• Improved erosion control.
• The ability to no-till with higher planter speeds.
• Faster harvesting speed.
• More bottom line profit.

Definitely a booster of ultra-narrow row corn, Calmer is an Alpha, Ill., no-tiller who developed the single chain 15-inch corn harvesting head system. He’s convinced that the more uniform plant spacing found with ultra-narrow row corn reduces in-row competition between plants and improves sunlight interception that leads to higher yields.

With a population of 28,000 plants per acre, plants in 30-inch rows are spaced 7 1/2 inches apart, 11 inches apart in 20-inch rows or 15 inches apart in 15-inch rows.

7-Year On-Farm Trials

With four replications annually between 15- and 30-inch corn rows on his own farm over 7 years, Calmer has seen an average yield increase of 7 bushels per acre. The 15-inch corn outperformed 30-inch rows every year, with a yearly yield advantage that ranged from 6 to 10 bushels per acre.

5-Year On-Farm Trials

Calmer also has been involved in encouraging other farmers to do on-farm research. A summary of what 43 farmers in a dozen states have learned over the past 5 years is analyzed below.

In 381 side-by-side split-planter comparisons, yields were higher with 15-inch rows compared to…