Grass filter strips used on runoffs

By MANDY SPIKES | Central Texas Edition

September 11, 2003 -- An ongoing project, which is being conducted at the Texas A&M Blackland Research and Extension Center, tests grass filter strips to see if there is a reduction in the amount of herbicide runoff associated with crops near adjacent lakes, rivers, or streams. Included in the experiment are the herbicides atrazine and metolachlor.

"Filter strips are known to be a good buffer to sediment," stated Dennis Hoffman, research scientist at the center. "What I wanted to see is the impact that it has on other entities such as atrazine."

Atrazine is a crop herbicide used to control broadleaf weeds. Metolachlor is used to control grasses. The research, which began in 1990, examines the ways to reduce the amount of runoff associated with the two herbicides in an attempt to reduce the threat to bodies of water, such as streams and watershed, some of which are sources of public drinking water.

"Atrazine is a good product and one of the few herbicides that you can do pre-emerge, but we don't want it to be in the reservoir for public drinking water," said Monty Dozier, Extension specialist in water resources for Texas A&M University. "We want this product to be provided without any harm to the public. I give Hoffman a lot of credit on starting this project."

In field testing conducted at the Blackland Research Center, located in Temple, 30-foot-wide bermudagrass filter strips were planted next to 1.5 acre corn experimental plots. A 180-foot concrete wing arm was used to collect runoff from each corn plot. This runoff flowed in the flume, allowing researchers to measure the volume and collect runoff samples generated by natural rainfall.

"What I found out from doing this experiment was that filter strips were a good way to capture atrazine, as well as other herbicides," added Hoffman.

Dozier stated, "It's hard to do large scale filter strips, but we found that the Blacklands are the best place for having these strips."

Hoffman said that, at the present time, filter strips were being used around the country so he felt that this was a great accomplishment from doing the project.

"In 1995, we had a filter strip conference and universities from all over the United States came," Hoffman continued. "We were able to compare notes of the success rates that we had with the filter strips and how well the research was going in other places."

"We are currently taking the information to the farmers in our area to help them with their best management practices," said Dozier.

Hoffman added, "I would like to see farmers consider using wheat filter strips on their land because wheat is an economical crop, especially in the Blackland prairies."