PLANT CITY — Mosaic announced Tuesday it will close its Plant City fertilizer plant at the end of 2017 for at least a year to cut costs and improve profitability.

The plant, on State Road 39 just south of the Hillsborough-Pasco county line, has a work force of 430. The company said it is offering 200 voluntary retirement incentive packages to its Florida employees and has created about 100 more open positions through a hiring freeze over the last several months.

"The hope is to place as many of those impacted employees as possible in open positions in the company's other facilities," Mosaic spokeswoman Jackie Barron said.

Mosaic has Florida operations in Hillsborough, Polk, Manatee and Hardee counties. Those not placed elsewhere will receive a severance package based on, among other things, their number of years with the company and pay.

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The Plant City facility opened in 1965 and has the capacity to produce 2 million tons of fertilizer a year, the company said.

"Our business performed well in the third quarter, notwithstanding the impacts of Hurricane Irma on our phosphates operations," Mosaic president and chief executive officer Joc O'Rourke said on a conference call to announce the company's third-quarter earnings.

"We are making the move in Florida for several reasons," he said. "Plant City is the highest-cost facility amongst our Florida operations, and it requires a disproportionate amount of sustaining capital each year."

Idling the plant, he said, should help the company optimize capital investments and allow it to increase production at its most efficient Florida facilities to offset the tons produced at Plant City. And it also gives the company the option to re-open the Plant City plant if demand grows.

"While these decisions are difficult and have impacts on our employees, today's actions put Mosaic in a strong position to benefit as market dynamics improve," O'Rourke said.

Check back at tampabay.com for updates to this developing story. Contact Richard Danielson at rdanielson@tampabay.com or (813) 226-3403. Follow @Danielson_Times