Citing "challenging" market conditions, Mosaic Co. said Wednesday it will idle one of its Saskatchewan potash mines for the rest of 2016, laying off about 330 workers.

Plymouth-based Mosaic is one of the world's largest producers of potash, which is used to make fertilizer. But potash demand is historically weak as farmers globally are struggling with low crop prices.

"Lower global potash demand and market prices require that we curtail production," Mosaic CEO Joc O'Rourke said in a prepared statement.

Mosaic will temporarily shut its mine in Colonsay, which has an annual production capacity of 2.6 million tons. The company's two other Saskatchewan mines, which have lower costs than Colonsay, will remain open.

Mosaic's potash mine in Esterhazy, Saskatchewan, is its largest, with twice the production capacity of the Colonsay operation. The company's stock closed at $27.41 Wednesday, up 93 cents.