Organic options to fight weeds with chemical-free weapons

To grow crops organically, farmers fight weeds with chemical-free weapons. One of the most common is a disk. Farmers rip out weeds and churn them into the soil with these disks. But it takes heavy tractors to do this efficiently, and large tractor tires compress the soil as they roll across the field.

The process also depletes soil organic carbon, which plants depend on for nutrients, moisture, and healthy bacteria. And after a field is turned, heavy rains and wind can erode the exposed soil University of Missouri soil scientist Kerry Clark and a team including researchers from the USDA Agricultural Research Service are working to get the best of both worlds.

Can organic growers fight weeds and increase soil health? Researchers know cover crops provide part of the answer. Cover crops anchor the soil with their roots. Some even add nutrients to the soil. That would take care of the soil health concern. But the question of weeds remains.

Clark and her team experimented with three methods. One method used cover crops instead of disks to suppress weeds. They compared this method to two other organic options: using cover crops but turning them under, and the standard disk use without a cover crop.

Matting cover crops is key to the first method. Instead of turning the cover crop under, it is flattened with a roller crimper. This is a long rolling wheel attached to a tractor. The flattened cover crop creates a matted barrier over the soil. Afterwards, researchers plant cash crop seed into the mat, often using disks to cut through it. If the cover crop was healthy and abundant, the mat will be thick enough to choke out weeds.