Mosaic Co. on Friday beat Wall Street's quarterly profit expectations, buoyed by strong potash sales in North America, which offset market weaknesses elsewhere.

Plymouth-based Mosaic, one of the world's largest fertilizer producers, reported second-quarter fiscal 2013 net earnings of $629 million, or $1.47 per share, up from $1.40 per share a year ago.

Excluding one-time tax benefits, Mosaic posted profits of $1.05. Analysts polled by Thomson Reuters were expecting per-share profits of 93 cents, excluding one-time items. The company's stock reacted by rising $1.85, or 3.3 percent, to close Friday at $58.62.

The quarter was a mixed bag for Mosaic, which mines phosphate and potash, key minerals for fertilizer. Mosaic's operating earnings, a measure of profit that excludes one-time losses and gains, fell 30 percent.

Its quarterly sales of $2.54 billion fell short of the $2.57 billion forecast by analysts, and they were down 16 percent over a year ago. Both lower volume and lower prices stoked the decline.

But in North America, the company had "the highest levels of demand for our products since Mosaic was formed [in 2004]," CEO Jim Prokopanko told stock analysts in a conference call.

Joel Jackson, a stock analyst at Bank of Montreal, said North American potash volumes were better than expected. Mild weather helped prolong the fall fertilizer application season, he said.

However, "the strength in North America was offset by international offshore sales."

Exports to India and Canada -- two key global potash markets -- have been markedly down. "China and India continued to essentially sit on the sidelines during the second quarter," Jeffrey Stafford, a Morningstar analyst, wrote in a research note Friday. But some relief is on the way.

Earlier this week, a trio of potash producers in Canada announced a deal to sell 1 million metric tons to China during 2013's first half. Mosaic is one of those three producers, which together market Canadian potash under the name Canpotex.

Prices fetched in the China deal are lower than expected, but the sales volume is strong, Stafford said in an interview. "It removes some of the uncertainty surrounding the potash market."

Staff writer Adam Belz contributed to this report. Mike Hughlett • 612-673-7003