Making Cents Out of Weed Seed Banks

Weed seed "banks" – spots where many weed seeds lie dormant in the soil, creating a major nuisance for large farms as well as backyard gardens – are expensive to deal with. But Agricultural Research Service plant physiologists are working on inexpensive, environmentally friendly ways to control the banks to prevent weed problems.

At the ARS Water Management Research Laboratory in Fort Collins, Colo., Lori Wiles and Dale Shaner are studying ways to reduce the amount of herbicide needed to kill weed seeds.

Shaner is researching the relationship between electrical conductivity (EC) of the soil and herbicide binding. By discovering the EC of the soil, he hopes to be able to adjust the level of herbicide used, so farmers don't have to apply more than necessary.

Wiles is trying to find ways to map the seed bank in a field, so farmers will be able to apply chemicals only where needed, saving money and helping protect the environment. Because it's expensive to get large numbers of soil samples to produce an accurate map, Wiles is working on ways to reduce the cost. One plus is that the spatial distributions of weed seed banks are relatively stable, so farmers may only have to create a map every few years.

Also, Wiles has developed a software program, called WEEDSITE, to help growers investigate the value of site-specific management of weed seed banks in their cornfields.