The union representing workers at Nutrien's Rocanville potash mine estimates more than 500 people will be laid off during a temporary shut down in December.
On Monday, Nutrien announced it would be temporarily closing down its mine for two weeks starting Dec. 2. The company said it needed to cut production due to the CN Rail strike.
"It is extremely disappointing that in a year when the agricultural sector has been severely impacted by poor weather and trade disputes, the CN strike will add further hardship to the Canadian agriculture industry," said Chuck Magro, Nutrien's President and CEO, in a news release.
"Any further disruption will be harmful to our business, the Canadian economy, and Canada's competitive position and reputation."
Meanwhile the unions says workers at the mine were shocked at the announcement.
"Everybody's a little edgy, to say the least," said United Steelworkers Local 7916 president Jeremy Wray.
"We're just trying to be there for all the employees and their families."
Last week, CN workers with the Teamsters Canada Rail Conference went on strike, protesting working conditions.
Wray said the announcement came as a surprise, especially right before Christmas.
"It's terrible timing. We'll do what we can," he said.
The company and union are in talks to discuss how many workers will be kept on to maintain the mine during the shutdown.
In September, Nutrien announced it would be shutting down its Allan, Lanigan and Vanscoy potash mines for eight weeks during the last quarter of the year. The move, which was meant to slow down production in the face of low demand, was expected to reduce production by 700,000 tonnes.
Rocanville is located approximately 220 kilometres east of Regina.