Edge effect on corn a common occurrence

CHATHAM, Ill. — Does your corn have stunted, yellowing plants along the edges of the field?

If so, you’re not alone. It’s a common occurrence that agronomists call edge effect.

Edge effect is often caused by corn microclimate and weather patterns, according to agronomists at Pioneer.

How It Works

• Reduced corn yield along field edges can be associated with the effect of incoming winds on the microclimate within the field.

• Hot, dry air hitting the leading edge of a field increases evaporative demand and amplifies heat and drought stress along the field edge.

• The air picks up more moisture as it moves across the field, so plants in the interior experience less stress than those on the edge.

This effect is most pronounced when soybeans, hay or pasture are located adjacent to the cornfield. It’s often observed on the southern or western sides of the field.

“Competition for water resources between corn plants, neighboring field crops or grass from the ditch can be the main cause of edge effect,” said Matt Montgomery, Pioneer field agronomist. “This issue is only intensified during bouts of high wind and dryness.”

Higher temperatures naturally increase crop water demand by creating a higher vapor pressure deficit between the saturated leaf interior and the ambient air.

Corn plants respond to higher VPD by closing their stomata and preserving water. This reduces the rate at which plants take in CO2, lowering the rate of photosynthesis and potentially hurting yield.

It also increases soil water supply depletion, which can cause longer-term stress on the crop, Montgomery said.

Plants on field edges may also be at greater risk for sunscald, which occurs when evaporative demand increases faster than the plant is able to respond, causing leaf tissue to die.

“The environment we run into day in and day out is dynamic,” Montgomery said. “Understanding that plants are constantly competing for many of the same nutrients and moisture helps explain yellowing corn and edge effect.”

While the yield impact of edge effect is often minimal, drought stressed corn — especially during grain fill — can lead to yield loss.