AMES, Iowa – An Iowa State University doctoral student in crop production and physiology has been focusing her research on how corn responds to nearby perennial groundcover, a system gaining attention for its ability to protect soil year-round.

Amina Moro’s paper, “Spatial Proximity to Perennial Groundcover Triggers Shade Avoidance Responses in Corn,” was recently published in the Journal of Agronomy.

“Perennial groundcover systems are very promising because they keep the soil covered year-round, improving soil health, reducing erosion and enhancing sustainability,” she said. “But farmers are hesitant to adopt them because of concerns about competition with corn, especially early in the season.”

She said her research challenges a common assumption, that competition between plants begins only when they compete for water or nutrients. Instead, she found that competition may start much earlier, through light signals that plants use to detect nearby neighbors.

At the center of her study is a concept called shade avoidance response, in which plants can sense when other plants are nearby even before they are physically shaded: “When corn detects changes in light quality, it interprets it as a sign that competition is approaching,” she said. “It responds by growing taller and reallocating energy toward vertical growth.”

In her research, an experimental unit consists of two strips of grass and three pots of single corn plants. The corn and grass root zones were physically isolated using separate containers on a 25 by 50 (centimeters) cm tray, with three corn pots and grass strips positioned at assigned distances (0, 6 and 25 cm) along the tray edges to establish different above ground competition patterns.

She said while this might sound beneficial, it comes at a cost: “Taller plants often develop thinner stems and reduced structural strength, which can lead to lodging and reduced efficiency later in the season.”

She said one of the most significant findings from her study is that proximity, not just the presence of groundcover, determines how corn responds: “We observed that corn begins to respond at very short distances. At 6 cm, plants already initiated a shade avoidance response, but at 25 cm, they behaved as if there were no competition.”

She added even more striking, when corn was in direct contact with groundcover, the stress reduced growth entirely.

This insight has important implications for how cropping systems are designed. Rather than eliminating groundcover, farmers may simply need to adjust spacing.

Susana Goggi, ISU professor of agronomy and Moro’s adviser, said this research addresses one of the most pressing challenges in modern agriculture: balancing soil health with crop productivity. “The use of perennial groundcover is a game changer. It can reduce soil erosion, water runoff and nutrient loss. But it also creates microclimatic changes that can affect crop growth.”

Moro said her work is helping to identify the ideal distance between crops and groundcover that preserves environmental benefits without sacrificing yield. She said by maintaining a small buffer zone – around 25 cm – farmers can prevent early stress signals in corn, while still benefiting from soil protection.

She said her findings also highlight the importance of hybrid selection, adding that some corn varieties are more sensitive to shade signals than others, meaning farmers can further optimize performance by choosing the right genetics.

“Farmers do not have to choose between improving soil health and maintaining yield,” she said. “With the right combination of spacing, hybrid selection and management practices, it is possible to design systems where corn grows efficiently, while the soil remains protected.”

Mark Licht, ISU associate professor of agronomy and extension cropping systems specialist, told Farm World, “At this point, perennial groundcovers come with production risk; however, this and others research are going to reduce that production risk with the ultimate benefit being reducing erosion, reducing phosphorus loss, and reducing nitrogen loss. This type of research is needed to help farmers balance productivity, profitability, and environmental goals.”