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Bale grazing may increase nutrient loading, say researchers

Not so green Practice of in-field winter feeding may not make the 
Beneficial Management Practice list

Winter feeding cattle on pasture has long been pitched to ranchers as one of the best things they can do to help the environment and their own bottom line.

But new research on the Pipestone Creek watershed in Saskatchewan shows that it may not be as green as earlier suggested.

“It’s controversial only because you have to be very careful where you do it,” said Barbara Cade-Menun, an environmental scientist with Agriculture and Agri-Food Canada and SPARC.

Cade-Menun, the lead researcher at the Pipestone Creek Watershed Evaluation of Beneficial Management Practices (WEBs) project in the “knob-and-kettle” pothole country south of Whitewood, Sask., said that analysis of run-off water from bale grazing sites has found extremely high concentrations of nutrients and harmful bacteria.

“When we set this up, there were a lot of people who were hard-core believers that this was a great practice,” she said, as she guided a tour group through the WEBs site’s various research points that were installed on three area farms in 2008.

“And then they saw the colour of the water coming off of those sites compared to the controls.”

Coloured water

Bale grazing, a practice in which winter feed supplies are placed in a grid pattern and doled out to cattle row by row with portable electric fences, is used by many ranchers to restore fertility to depleted pastures and hayfields.

Proponents point to hefty savings in fuel and wear and tear on tractors during the winter, and the elimination of associated costs of cleaning out and spreading manure accumulated in dry-lot pens in spring.

But Cade-Menun said that fecal coliform counts in the run-off water from the test sites were 200 times higher than allowed, and researchers were advised to wear disposable gloves when handling samples.

Economists working on the project estimate it saves about $25 per head on the cost of wintering a cow.

“But that doesn’t take into account what happens when you pollute your neighbour’s well and they’re mad at you and sue,” said Cade-Menun.

Dena McMartin, from the University of Regina, said that recommending bale grazing as a BMP is “more economic than environmental.”

“You save on time, fuel, and the animals are happy and healthy in one place,” said McMartin, as she explained water testing equipment at the two bale grazing sites, one control where no manure was spread, and one where manure from dry-lot pens was mechanically spread in spring.

Fecal coliform, also known as E. coli, inhabit the guts of all warm-blooded animals. But when they enter the water supply, they can make people sick, as evidenced by the Walkerton tragedy.

Snowmelt

In normal years, most of the water flow on the Prairies happens during spring snowmelt. For about two days each spring, run-off collected on the gentle slope downhill from the bale grazing site exceeded all water quality guidelines, she said.

“We’re seeing water that is not safe to drink for humans or animals, and not safe to swim in,” she added. “We’re seeing a large flash, or pulse, of microbes leaving the fields.”

At that particular site, the run-off “probably” stays on the field and doesn’t make it into the main stem of the Pipestone Creek, which runs across the border into Oak Lake in Manitoba, into the Souris River, the Assiniboine, the Red and eventually Lake Winnipeg.

Dave Barrett, from the University of Regina, has been looking at how sediments from the site can ferry pathogens farther downstream via “flocs,” a kind of microscopic raft.

“It’s allowing longer survival times for bacteria,” he said. “These larger particles can transport nutrients as well.”

Preliminary results are showing that about 50 per cent of the bacteria in water are associated with sediments, he added.

Kyle Hodder, also from University of Regina, said that one “flash” rainfall event — just shy of an inch in under an hour — this past summer stirred up an amount of sediment that was “higher than anything he’d ever seen,” even in his past experience in mountain glacier environments, typically deemed the most prone to suspended sediment movement.

“The water was almost black with sediment,” said Hodder. “In Saskatchewan, this summer, at this site, we had three times higher concentrations than any of those glacier environments.”

Questionable

McMartin said that the research shows bale grazing’s status as an environmental BMP is questionable.

“It doesn’t seem to hold back sediments, particulates, and it produces high numbers of bacteria,” she said.

Cade-Menun added that more evaluation of all BMPs is needed to see if they truly perform as advertised before public money is spent on promoting their widespread adoption.

“A lot of these BMPs are done without testing,” she said. “They just sound good on paper.”

But Brook Mercer, the landowner on the site, who mob grazes 800 head of cattle in 40-acre paddocks, believes the nutrient-capturing benefits of bale grazing outweigh the potential downsides.

“We’ve got bale grazing sites where the grass is so thick you can hardly drive through with a quad,” he said. “You get years and years of benefits.”

Linda Corcoran, a rancher also on the tour, added that she believes the researchers haven’t studied the issue long enough to see if the nutrients and bacteria are actually making their way into the creek.

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