WINNIPEG, Manitoba (BLOOMBERG) - Canadian Prime Minister Justin Trudeau's push to accelerate the fight against climate change is sparking a showdown with the nation's farmers, who say it's threatening food supplies - and their profits.

The government is proposing to cut emissions from fertiliser by 30 per cent by 2030 as part of a plan to get to net zero in the next three decades.

But growers are saying that to achieve that, they may have to shrink grain output significantly at a time when the world is scrambling for more supplies. Also at stake is the estimated C$10.4 billion (S$11.2 billion) that farmers could lose this decade from the reduced output.

The tension comes as efforts to cut carbon dioxide emissions related to energy are lagging, so policymakers are increasingly looking to other sectors, including agriculture.

Climate targets on nitrogen in the Netherlands, for example, spurred protests from farmers worried they'd be forced out of business. Cattle and fertiliser are key sources of nitrogen emissions.

Angry Dutch farmers brought cows to parliament, threatened to slaughter them and blockaded food distribution centres serving major supermarkets.

"If you push farmers against the wall with no wiggle room, I don't know where this will end up," said Gunter Jochum, president of the Western Canadian Wheat Growers Association, which represents growers who farm about 1.2 million hectares. "Just look at what's happening in Europe, in the Netherlands. They've had enough of it."

Production losses could be significant, according to an analysis commissioned by Fertiliser Canada. Canada could lose over 160 million metric tonnes of canola, corn and spring wheat between 2023 and 2030 due to the plan, according to the report. That's nearly double Canada's expected grain production this season.

Agriculture emissions have soared in recent decades as farmers apply more fertiliser to increase output.

Emissions from crop soils rose 87 per cent to about 7.6 metric tonnes of carbon dioxide over three decades through 2020, according to the latest data from Environment and Climate Change Canada.

By comparison, emissions from oil and gas extraction more than tripled by 69 metric tonnes of carbon dioxide in the same period.

Farm groups say the additional fertiliser is resulting in more food. Spring wheat yields rose more than 40 per cent in the last decade through 2020, compared with the 1990s, Statistics Canada data show.

Similarly, canola yields rose 56 per cent over the same period.

"We are talking about the food supply," said Karen Proud, chief executive officer of Fertiliser Canada, an industry group that represents major manufacturers and retailers, including Nutrien Ltd., and Koch Fertiliser Canada.

"Canada is already among the top countries that use nitrogen efficiently. We don't have much room to go before we start affecting yields."

While the reduction target is "ambitious", it does not "represent a mandatory reduction in fertiliser use" and action will focus on improving nitrogen management, Cameron Newbigging, spokesman for Agriculture and Agri-Food Canada said in a statement.

The approach for achieving reductions is still under development and the government is accepting feedback until Aug 31 and will develop "next steps in the approach" once the consultations are complete, he said.

Farmers are already trying to reduce their fertiliser usage because costs have skyrocketed. They're using specialised equipment to apply it more efficiently, Wheat Growers' Jochum said.

Government incentives to offset the cost of new equipment or soil testing could help reduce emissions without jeopardising food production, said Jim Everson, president of the Canola Council of Canada.

"I hope there is an ability for the government to listen," said Bill Campbell, president of the Keystone Agricultural Producers. "I certainly hope the policies don't become reactionary."

Saskatchewan grower Ian McCreary says more education is needed to help farmers cut fertiliser usage.

McCreary, a member of Farmers for Climate Solutions, estimates his fertiliser usage dropped by as much as 20 per cent per acre (0.4 hectare) after he spent C$50,000 in equipment changes, and mapping and testing the soil on his farm to determine how much nitrogen he needs.

The move probably saved him C$20,000 in input costs this year and hasn't reduced yields, he said. "We've simply taken nitrogen out of areas of the field that weren't using it anyway," McCreary said.