The Mosaic Co. is temporarily laying off about 330 employees as it idles its potash mine in Colonsay, Sask.

The company said Wednesday that it will rely on its lower-cost Esterhazy and Belle Plaine mines in Saskatchewan for potash production during a down-market for the fertilizer.

"The potash market has just proved to be quite challenging this year," said Mosaic spokeswoman Sarah Fedorchuk.

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She said the company has set Jan. 3 as the restart date for the mine, but that could change based on market conditions.

"It's our hope that market conditions will improve and we can recall our workforce earlier, and we are watching the market very closely," said Fedorchuk.

Mike Pulak, a United Steelworkers union staff representative, says about 368 unionized workers are affected by the temporary layoffs, including some on short– and long-term disability. Pulak said about 32 unionized staff will be kept on for safety checks and maintenance.

He said the job cuts could be in response to workers at Colonsay overwhelmingly voting down the company's latest contract offer on Monday, but Fedorchuk rejected that suggestion.

"A decision of this magnitude requires a lot of thought and a lot of preparation, and it's not something that we would make overnight, or be reactionary because our offer was rejected," said Fedorchuk.

Unionized workers at the Colonsay mine, which is located about 75 kilometres east of Saskatoon, have been without a contract for 15 months. Last October, Mosaic permanently cut 46 jobs at the mine after deciding to reduce production, citing an oversupplied market.

Other potash producers have also cut back, with the Potash Corporation of Saskatchewan Inc. shutting down its Picadilly mine in New Brunswick in January, putting 430 people out of work, and Vale suspending work at its potash mine at Kronau, Sask., last November.