Lower phosphate and potash prices and several unplanned events resulted in a net first-quarter loss of $1 million for the Mosaic Co.

Earnings per diluted share were at the break-even level, well short of the 19 cents per share expected by analysts polled by Thomson Reuters and 73 cents less than earnings in the first quarter of the previous year.

In the first quarter of 2016, the company had net earnings of $257 million.

The global fertilizer company based in Plymouth said Tuesday its net sales during the quarter were $1.6 billion, down from $1.7 billion during the same period in 2016, with the lower prices more than offsetting higher sales volumes. Prices are at multiyear lows in part because of the weak farm economy and low crop prices, which have forced farmers to reduce fertilizer and other expenses.

Mosaic's report sent its share prices spinning downward to the lowest levels in 7 months. President and Chief Executive Joc O'Rourke called the first-quarter results "disappointing," but said that global demand is strong, and the company will benefit from higher sales and prices during the rest of the year.

"Mosaic is well positioned to capitalize on the gradual recovery in potash and phosphate markets," he said.

In a conference call with analysts, Rich Mack, Mosaic's chief financial officer, said the company also experienced several operational challenges that hurt earnings during the quarter.

The company had a mechanical failure at its Esterhazy K2 potash mine in Saskatchewan, an unplanned shutdown of its Faustina ammonia plant in Louisiana, excessive rain and flooding at a joint venture mine that it owns in Peru, and a derailment and other logistical problems at Canpotex, a potash operation in Canada that Mosaic owns with two partners.

Some of those problems overlapped into April, Mack said, so they will also affect next quarter's financial results somewhat.

"We expect the second-quarter margin rate to increase compared to the first quarter, but we also expect that it will be negatively impacted" because of costs related to the shutdowns, he said.

On the brighter side, O'Rourke said, prices should recover a bit in 2017 because Chinese production and exports of phosphate products are expected to decline later in the year. The changes are being driven by Chinese concerns that some of its older and inefficient production facilities need to be shut down and rebuilt to become profitable and reduce air and water pollution.

And demand for phosphate products continues to be robust in Brazil and India, he said, as well as in some emerging markets.

O'Rourke said a priority for the company this year is completing the transaction to acquire Vale Fertilizantes, the fertilizer unit of Vale SA, a Brazilian company. Mosaic agreed to purchase the business last December for about $2.5 billion to strengthen its presence in South America.

Mosaic will be paying "a great deal of attention" to closing the deal later this year and integrating its operations, O'Rourke said.

Shares traded down 7 percent, or $1.92, to close Tuesday at $24.95.

Tom Meersman • 612-673-7388