Narrow strips of vegetation along farm field edges can help keep sediments and pesticides from draining into adjacent streams, a University of Nebraska study indicates.

These plantings, known as riparian or vegetative buffer strips, can contain a variety of vegetation and be of different widths. They're planted between farm fields and the streams they drain into.

"Most of the early research was done in the east and southeast United States and what they've found there doesn't necessarily hold with what we're seeing here," said Kyle Hoagland, aquatic ecologist in NU's School of Natural Resource Sciences.

Research elsewhere indicates strips should be at least 95 feet wide to effectively control runoff.

In this Nebraska research, Soil Scientist Mike Dosskey, graduate student Tim Schmitt and Hoagland focused on 25- and 50-foot wide strips at NU's Agricultural Research and Development Center near Mead.

Four different vegetative cover types were compared for each of the two widths: 25-year-old native grasses; 2-year-old grass; 2-year-old grass with trees and shrubs; and cultivated grain sorghum.

Grass strips, with or without trees and shrubs, effectively reduced sediment runoff, but were less effective in reducing dissolved contaminants such as atrazine and nitrate. Doubling strip width didn't necessarily improve sediment settling.

Grass strips also show promise for more effectively removing contaminants as the grass matures.

"The 25-foot buffers removed most of the sediment and sediment-bound contaminants, but 50 feet or more appeared necessary for similar control of dissolved contaminants such as atrazine and nitrate," Hoagland said.

While sorghum worked better than anticipated, grass strips were more effective at reducing sediments. Filter strips' effectiveness could be closely linked to their design and the crops and cropping practices for which they substituted.

The Nebraska Department of Environmental Quality through the U.S. Environmental Protection Agency, Region VII helped fund this research.

- Steve Ress

Soil Scientist Mike Dosskey checks buffer strips planted at NU's Agricultural Research and Development Center near Mead.