While the USDA estimates only about 10% of U.S. cropland is being managed with cover crops for various soil health and weed suppression reasons, recent research across the Corn Belt shows over-wintering cereal crop covers can significantly reduce weed biomass.

While on-farm and research results vary widely, an early 2023 symposium of the Weed Science Society of America revealed several core trends tying cover crop use to weed suppression. Get Rid of Weeds (GROW), a collaboration of integrated weed control among land-grant universities, reports the following takeaways from the symposium:

1. Biomass is Key

The more biomass a cover crop produces before termination, the greater the likelihood of successful weed suppression.

LIVING MULCH. Cotton planted between a living mulch of white clover showed fewer Palmer amaranth weeds for two seasons after the university trial began. UGA Crop and Soil Sciences Weed Science

“A thick mat of residue can suppress weeds’ germination, emergence and reproduction, as well as aid in decay of weed seeds beneath it,” says Erin Haramoto, University of Kentucky weed scientist.

Haramoto is quick to note that not all regions of the country can consistently produce the biomass figures that seem fairly consistent in the Mid-Atlantic area with its warm springs and ample rainfall.