Mosaic Co.'s fourth-quarter earnings far surpassed expectations as demand for fertilizer spiked, validating a rebound its chief executive predicted in the face of losses a year ago.

Profit for Plymouth-based Mosaic, one of the world's largest fertilizer producers, more than doubled to $361 million in the three months ended Dec. 31, the company said Wednesday. Revenue rose 9 percent to nearly $2.4 billion.

The profit amounted to 97 cents a share, exceeding the consensus estimate of analysts surveyed by Thomson Reuters of 86 cents. Mosaic shares rose nearly 1 percent on a mixed day in the broader market.

Floundering prices for potash, one key ingredient in fertilizer, led to a plunge in the company's results in late 2013. But Mosaic Chief Executive Jim Prokopanko at the time gave an upbeat outlook, saying, "We are starting to see some rays of sunlight at the end of this tunnel."

During a conference call with analysts Wednesday, Prokopanko recalled that comment.

"Our predictions don't always come true, but in this case, it's very gratifying to be proven right," he said. "The sunlight was real, and Mosaic was and is in excellent position to benefit in better parts of the business cycle."

To make fertilizer, Mosaic mines potash and phosphates. Prices for both, $295 for potash and $448 for phosphates, fell in the upper ranges of estimates during the latest quarter.

Mosaic said it sold less phosphate than a year earlier, but higher prices compensated for the lower volume. And although potash prices dipped on average, production levels increased significantly. Mosaic reported selling 2.3 million tonnes of potash, compared to 1.9 million tonnes last year.

Investors should expect the company's strong performance to continue this spring, Prokopanko told analysts. The company forecast a small drop in potash sales volume for the January to March quarter and held its pricing outlook for the mineral. It said it expects a gain phosphates volume and a slight rise in price.

Tyler Gieseke is a student at the University of Minnesota on assignment for the Star Tribune.