COLONSAY, Sask. - The Mosaic Co. says it is cutting about 350 workers at its Colonsay potash mine in Saskatchewan as it ramps up production at a lower-cost operation.

The fertilizer giant says it has issued 395 layoff notices to hourly workers as it indefinitely idles the Colonsay mine, but expects 52 of those workers to stay on to keep the operation on standby in case market conditions improve.

The move comes after unprecedented wet spring weather in North America disrupted the planting season and affected fertilizer demand, though potash prices still rose.

The company says it will make up for the lost Colonsay production by relying both on inventories and production at its lower-cost Esterhazy K3 project in Saskatchewan that it has been developing for years.

The company committed $1.7 billion in 2015 to accelerate development of the Esterhazy K3 project. The mine, expected to be at full production by 2024, has produced over 400,000 tonnes of ore in the first half of this year.

Mosaic says the mine closure and production shift are expected to avoid US$40 million to US$50 million in cash spending this year.