Tending to the biobeds. Researcher Tom Wolf says this should become a viable pesticide disposal option for producers in the years ahead.

Biobeds show promise for safe, efficient pesticide disposal

By now, many Canadian producers have heard about biobeds – a method of "composting" pesticides that has been used in countries in Europe for many years. The question on many of their minds is "Can I use one to dispose of pesticides on my own operation?"

Posted: September 22 2009

The answer, says lead researcher Tom Wolf with Agriculture and Agri-Food Canada (AAFC) in Saskatoon, is not yet. Although biobeds have proven successful elsewhere and preliminary research in Canada points to long-term success, Wolf says there are still several things to find out about how biobeds work on Canadian farms. Once that work is done, a lengthy regulatory process would most likely follow before they can be used for pesticide disposal in Canada.

To Wolf, however, biobeds are one part of the greater work of opening up a dialogue on pesticide disposal, a practice he says has become cumbersome, time-consuming and confusing in today's regulatory environment. "The big deal with biobeds, in my opinion, is that we've always kind of swept the pesticide disposal issue under the carpet. We've never openly talked about how you as a farmer deal with your pesticide waste. What do you do with it? Where do you put it? How do you put it there?

"We would like to address this issue in a practical way so that we have, with a reasonable amount of effort, a reliable way to dispose of the waste that we know is bad for the environment. That, we hope, is going to be the contribution of biobeds."

What is a biobed?

Developed in Scandinavia and since recognized in the UK as a best management practice, a biobed, in its simplest form, consists of a clay-lined hole filled with a mixture of topsoil, peat or compost, and straw. This mixture provides an ideal habitat for microbes which essentially "eat" pesticides by breaking them down to the point where they present no threat of contamination.

Although the same breakdown process happens in soil, Wolf says biobeds speed this process by binding the material more tightly and degrading it more quickly. The research conducted by Wolf's team and funded by the Pest Management Centre indicated that 98 percent of 2,4-D broke down in the biobed mix after two to three weeks, while 10 weeks was required for similar breakdown in soil.

"All biobeds do is speed up a natural process fivefold to tenfold," says Wolf. "Biobeds also retain water for some time, allowing the microbes to break down pesticides to the point where the water is essentially clean by the time it runs out the bottom."

Key questions

'Hands-on' progress. Biobeds have proven successful elsewhere and preliminary research in Canada points to long-term success.

The biggest question, says Wolf, is whether a biobed will mesh with environmental conditions and farming practices throughout Canada. A key concern is temperature. Although the research team found that higher temperatures increased the rate of 2,4-D breakdown in the biobed mix, temperatures below 15°C strongly hindered breakdown.

Another major challenge is moisture. "A lesson from the UK is that water is a limiting factor," says Wolf. "Sometimes a big rainstorm comes along and waterlogs the biobed. We need to look at what we need in terms of drainage."

Other questions include the best times of year to use biobeds, how they handle the volume of spray washout typically generated in Canada, and how they work with other types of commonly-used pesticides. "A problem that can occur is that some pesticides may not break down as easily so you might wind up with a hazardous waste problem on your farm," he says.

What researchers do know, based on what they've seen so far, is that biobeds appear to be a fairly flexible agent. "There's no particular soil type that renders it unusable, although coarse textures are recommended over heavier soils because clay content simply makes hydraulic movement of the water more difficult," says Wolf.

They also know that biobeds are not suitable dumping grounds for undiluted pesticides. "We've tried putting a neat pesticide on a biobed and that overwhelmed it," he says. "However, it seems to work with even a little bit of dilution."

Next steps

The next steps for the research team come down to testing biobeds in more places throughout the country with a wider range of pesticides. In the process, they hope to come up with solutions to identified challenges. "We're going to look at above-ground biobeds to reduce drainage issues. We will probably look at lining a biobed and coming up with some ways to pump it back to the top so you have some evaporative loss as well as transportative loss of water."

With so much work to be done, there's no telling how long it will be before Canadian farmers have access to safe, effective biobeds. Part of the problem is that his team - which includes Brian Caldwell and Allan Cessna of AAFC Saskatoon and Diane Knight and Rich Farrell with the University of Saskatchewan – is currently the only research team in North America dedicated to studying biobeds so, at least for the time being, the entire research burden rests on their shoulders.

And then there's the regulatory approval process to consider. Although this is typically a lengthy process, Wolf says the experience in the UK, where biobed regulations were fast-tracked, offers some reason for optimism. "It's promising because maybe we'll have a similar experience," he says.

One positive sign on these shores is the fact that Bayer CropScience is funding the next phase of the study with financial support for a graduate student and a biobed installation at one of their research farms. "The company has been supportive of similar initiatives in Europe and brings a host of experience to the project," says Wolf.