Computer modeling is helping find ways to reduce herbicide runoff into rivers and streams in the Blue River Basins that can affect downstream drinking water quality.

The University of Nebraska and Kansas State University have teamed on a research and extension effort to reduce nonpoint source runoff pollution affecting drinking water quality in several Kansas communities, said Tom Franti, NU Institute of Agriculture and Natural Resources surface water management researcher.

The project focuses on how grain producers in the 9,700-square-mile Blue River Basins area of southeast Nebraska and northeast Kansas use and apply herbicides. Herbicide runoff from fields sometimes contains levels of atrazine and sediments that can contaminate Kansas' Tuttle Creek Reservoir, a major drinking water source for Kansas City, Topeka and other Kansas communities.

Franti and Brian Benham, an IANR water management engineer, collected atrazine runoff data in the Nebraska basin from 1994-1997 and used it in a computer model to evaluate atrazine losses from three common tillage practices.

"We then used the model to help determine what herbicide management and tillage practices hold the most promise for reducing the amount of atrazine runoff from fields," Benham said. They evaluated disk-till (conventional till), ridge-till (minimum till) and slot plant (no-till).

Early results indicate certain practices could reduce average annual atrazine runoff by 50 percent or more. They are: using pre-emergent incorporation broadcast application at planting or post-emergent broadcast application four weeks after planting with disk-till; using pre-emergent band application at planting and post-emergent broadcast application with ridge-till; or post-emergent broadcast application with slot plant.

"Our objectives with this research are to increase the use of best management practices to reduce the potential for atrazine runoff and increase the use of sediment control practices such as vegetative filter strips," Franti said.

A U.S. Geological Survey water resources research grant helped fund this research.

- Steve Ress

Joint NU and Kansas State University research focuses on how grain producers use and apply herbicides in the Blue River Basins.