Experts study microbes’ pesticide eliminating skills

OUTLOOK, Sask. — Pesticides washed out of a sprayer can account for up to 80 percent of the pesticides found in water bodies, European research has found.

That’s why biobeds have become popular on that continent.

Biobeds absorb the pesticides and degrade them to eliminate or reduce contamination.

The practice is still largely at the research stage in Canada, but Europeans have used it for the last 10 years.

Biobeds at the Canada Saskatchewan Irrigation Diversification Centre near Outlook appear like raised garden beds, tucked behind a building and sitting adjacent to a concrete pad where the rinsate is dumped.

The rinsate falls through a grate, is pumped to a holding tank and then dripped on to the biobed at certain intervals. Microbes in the beds break down the pesticide, and the water coming out after the process should be pesticide-free.

Agricultural engineer Larry Braul of Agriculture Canada said the evidence from Europe indicates that the process works, but Canada’s climate and weather present challenges.

“This biobed, on May 8, we probed down and eight inches below the surface it was solidly frozen,” he told participants at the centre’s recent field day.

“Microbes don’t do well in cold temperatures.”

Canada also experiences more torrential rainfalls than other places, which could affect how the microbes do their work, he added.

Agriculture Canada is working with Simply Ag Solutions in Saskatchewan and the County of Grande Prairie in Alberta to test different designs.

Canadian research is also focusing on the microbes.

The two beds at Outlook are designed to test differences, particularly if fungicide rinsate is dumped on them.

“The primary microbe that works on the biobed is something called a white rot mold, and it’s a fungi,” Braul said.

“If you have a fungicide, is that microbe being killed in the first biobed and possibly setting up better in the second one? It also adds a lot of robustness to it when you have two because they say most of the activity is in the top six inches of the biobed. We’re looking at the microbial population and the genotype.”

Braul said the results should tell researchers how they can improve the nutrients and perhaps even seed the biobeds with the correct micro-bes for a specific chemical.

A biobed is 25 percent soil, 25 percent peat or compost and 50 percent chopped straw or wood chips.

The soil contains the micro-organisms that have developed over time as a field is sprayed, so it introduces the microbes.

The wood chips provide a feed source for the microbes, and the compost, which is high in organic matter, absorbs the pesticides.

Activity increases as the mixture warms, and the rate of degradation is higher.

Braul said the material can work for five to seven years and then should be replaced.

“The general recommendation is to compost it for a year and then to spread it on your field,” he said.

“That gives the microbes another year to finish their work.”

Collection pads can be expensive concrete or simple pits.

“In Europe, sometimes they build a biobed and they put grating down and they drive right onto the biobed when they wash off their sprayers.”

Braul said researchers hope to develop a manual within a few years so Canadian farmers can use the practice to limit sprayer runoff.

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