Plymouth-based The Mosaic Company on Monday posted a 196 percent increase in first-quarter net earnings, fueled by a nearly 50 percent increase in sales.

Net earnings for the quarter that ended August 31 totaled $297.7 million, or 67 cents per share, a significant improvement from last year’s first-quarter net earnings of $100.6 million, or 23 cents per share.

First-quarter sales also showed improvement, totaling $2.2 billion-a 47 percent increase from $1.5 billion in the same period last year.

In addition, first-quarter operating earnings were $410.3 million, a significant improvement from $134.2 million in the same period last year.

Net sales in the company’s phosphates segment were $1.6 billion for the first quarter, up from to $1.2 billion last year. Operating earnings in the segment were $178 million, compared to $46.5 million in the prior year. The company said that the improvement in operating earnings was primarily due to higher phosphate selling prices.

The company’s potash segment had net sales of $621.9 million for the first quarter compared to $333.3 million a year ago. Operating earnings totaled $218 million in the first quarter, compared to $99.3 million in the prior year. The improvement was due to significantly improved sales volumes, partially offset by a decline in selling prices.

Shares of the company’s stock were up 3.4 percent at close on Tuesday to $60.80.

Mosaic is among Minnesota’s 15-largest public companies based on its 2009 fiscal-year revenue, which totaled $10.3 billion. The company reported $6.8 billion in revenue in its most-recently completed fiscal year, which ended on May 31.

-Melissa Loth