University of Alberta researcher Gurpreet Singh said he unearthed scientific evidence that composting, rather than the normal farm practice of stockpiling dung, produces a third less greenhouse gases and could reduce Canada's carbon emissions by as much as 1.6 billion kilograms annually.

Composting also creates a "better textured" fertilizer that is easier to spread on fields and reduces its pungent odor, he told AFP in a telephone interview from Edmonton in western Canada.

But, the high cost of composting -- as much as 50,000 Canadian dollars (43,000 US dollars) for special tractor-fitted turning equipment plus annual labor costs -- will likely turn off most farmers, despite the obvious environmental benefits, industry observers said.

Singh spent three months folding and mixing a massive 50-tonne pile of cow dung, while another pile was left untouched.

The static pile generated 233 kilograms of carbon dioxide emissions per tonne, while the turned pile emitted a mere 92 kilograms of equivalent carbon dioxide, he said.

In inert mounds, microbes starved of oxygen also produce methane gas as they feast on the feces, he said.

Agricultural waste emissions -- methane, carbon dioxide and nitrous oxide -- are Canada's fourth largest source of greenhouse gases.

Alberta province is home to 40 percent of Canada's five million cows. Its two million cattle generate an estimated 4.4 million tonnes of manure annually, Singh said.

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