Cows identified as gas emitters

OTTAWA - Big oil and gas companies aren't the only problem in the fight against heat-trapping gases.

An environmental report warns farming, fertilizer and diets are responsible for a large chunk of the pollution blamed for global warming. The Greenpeace report, Cool Farming, estimates direct and indirect agriculture industry activities are contributing 17% to 32% of global greenhouse gas emissions. Overuse of fertilizer is believed to be one of the leading culprits, releasing an estimated two billion tonnes of nitrous oxide -- a greenhouse gas estimated to be 300 times more potent than carbon dioxide -- into the atmosphere.

While Greenpeace Canada is urging the Harper government to implement a new tax on fertilizers, converting the new revenues into assistance for greener farming practices, the report's author, Pete Smith, a professor of soils and global change at the University of Aberdeen, also suggests consumers have a role to play.

"This is not [about] having a go at farmers," said Mr. Smith, a lead author of the Intergovernmental Panel on Climate Change's 2007 report.

"This is just trying to look forward to the future and see how we can move forward in a sustainable way that's both climate-friendly and allows us to feed the people that we need to."

Mr. Smith said the agriculture industry could become a net sink for greenhouse gas emissions, instead of a source, if it improves land use and management, and restores organic soils through activities such as re-planting grasses.