Research has shown that vegetative buffers are very good at controlling sediment and keeping it out of waterways. But what about reducing herbicides?
"We have a major problem with that in the claypan soils in northeast Missouri," said Bob Lerch, a soil scientist with the USDA Agricultural Research Service and an adjunct assistant professor at the University of Missouri.
Lerch and his ARS colleagues decided to see how well buffers reduced herbicides in soils with high runoff potential.
In 2004 the researchers began working with buffer plots at the MU College of Agriculture, Food and Natural Resources' Bradford Research Center that had been used for studies focusing on sediment and nutrients. They conducted a preliminary study to see if buffer plots would work at all for herbicides.
"We got some nice results and then started a longer-term experiment that went from 2006 to 2010," Lerch said. "We looked at four different buffer treatments involving different types of grasses."
The grasses were tall fescue, a cool-season grass and the most common grass in Missouri; tall fescue with a switchgrass hedge; a mixture of warm-season grasses including Indian grass, switchgrass and eastern gamma grass. A fourth treatment used no vegetation.
Plots were split in two. The lower part had the buffer. The upper part was sprayed with a chemical, which was sampled as it went through the buffer.