Corn Edge Effect: Possible Solutions to Test Out

April 4, 2023 3:56 PM
Blog Post

This post is not to explain what corn edge effect is or what is causing the phenomenon but rather throw out a couple thoughts on possible solutions. Briefly, corn edge effect is when yields around the outside of a corn field are significantly lower than in the middle of the field due to a wind induced microclimate. The effect of reduced yields is much more severe under hot and drier conditions which is why it has been much more noticeable over the last couple of years. It also tends to be worse on the west or south field edges. And the effect cannot be attributed to compaction or herbicide drift.

Before stating some possible solutions, I must for qualify that these are only POSSIBLE solutions. I do NOT have research or on-farm trial evidence these possible solutions will work. To test these solutions, it would take cooperation with farmers/agronomists and financial support.

Short-term solutions that should be considered are changes to management practices that can improve water use efficiency or stress tolerance to drought conditions. Here are three hypotheses to consider or test out in an on-farm trial this summer.

  • Hypothesis A: The use of a drought tolerant hybrid or workhorse hybrid will respond better across the width of the affected area as these hybrids should have greater stress tolerance.
  • Hypothesis B: Increase the corn seeding rate 10% to 15% around the outside of the field to create a denser wall thereby reducing the distance edge effect extends into the field.
  • Hypothesis C: Decrease the seeding rate by 10% to 15% across the ‘affected area’ to lower field water demand (i.e. reduce competition for limited soil available water).

While short-term changes to management will be beneficial more immediately, don’t rule out the possibility of management changes for long-term effectiveness. The following two hypotheses have the potential to increase available soil water holding capacity and resiliency 5+ years after establishment.

  • Hypothesis D: Adoption of cover crops will increase soil organic matter and soil water holding capacity thereby increasing resiliency to drought conditions.
  • Hypothesis E: Adoption of no-tillage or strip-tillage to reduce the amount of soil water evaporation from the soil surface and preserving available soil water for plant use.

Designing an on-farm field trial to test these hypotheses does take some consideration and adaptation from the way on-farm trials are traditionally carried out. Because the effect is on the edge of the field, selected fields must not have compaction from end-row traffic. Care must be taken to rule out herbicide drift and confounding effects from changes in management practices.


Mark Licht Associate Professor

Dr. Mark Licht is an associate professor and extension cropping systems specialist with Iowa State University Extension and Outreach. His extension, research and teaching program is focused on how to holistically manage Iowa cropping systems to achieve productivity, profitability and en...