COVERING hog manure storage ponds can cut the stench from hog farms in half, but Manitoba's rules for buffer zones might not be strict enough, a University of Manitoba researcher has discovered after deploying a team of sniffers.

Qiang Zhang, head of the department of biosystems engineering, trained helpers to record odours downwind of hog barns, with the co-operation of the owners.

He's trying to bring a little science to the emotionally-charged debate in farm country over how much stink is acceptable.

Comparing a farm that kept its liquid manure in an open pit to one with a negative pressure cover, he found the odour coming from the covered storage area was negligible.

Covered manure also emitted much less carbon dioxide and somewhat less ammonia. Both are so-called "greenhouse gases" believed to contribute to the global climate change Canada is committed to trying to reduce.

On the open manure farm, the pungent odour coming from the barns themselves was responsible for about half the odour problem.

Zhang also looked at different models for assessing how far barns and manure ponds should be from the nearest home. He recommends the Minnesota model, which would require setback distances slightly higher than the chart used in Manitoba.

On the other hand, Manitoba's rules for how far hog farms need to be from the nearest town or recreational area might be too high, he said.

Ruth Pryzner, a farmer and municipal councillor in the Rural Municipality of Daly, is concerned the Doer government's new planning act might give the province the power to overrule municipalities that set larger buffer zones than the province.

Winnipeg environmental activist Glen Koroluk said odour is one thing, but Zhang's research does not address the health issues associated with breathing fumes from hog farms. Koroluk wants gaseous emissions like sulphur dioxide regulated by the province as they are for the oil and gas industry.

Research has shown potential harm to workers inside hog barns, but the hazards faced by downwind neighbours are subject to more debate.

Zhang said keeping barns cleaner and reducing the amount of spilled feed and water cuts the intensity of odour neighbours have to put up with.

"It doesn't actually require a lot."

Oil sprays can be used to reduce the dust inside barns and biofilters can help clean air being sent out through exhaust fans, Zhang said.

The project received funding from the Manitoba Livestock Manure Management Initiative.