Fertilizer maker Mosaic Co posted a 91 percent drop in fiscal first-quarter profit on Monday, but expressed optimism that farmers would increase fertilizer purchases in the near future.

Farmers, many of whom had stocked up on fertilizer earlier this year on fears prices would rise even higher, held back on purchases of key nutrients needed for crop production during the quarter that ended August 31.

The company, which is majority owned by Cargill Inc , said it remains optimistic that farmers will apply more fertilizer for next year's crop.

Industry analysts worry that because the 2009 corn crop went in late, there may not be time for a fall fertilizer application.

We believe farmers will increase application rates in response to high 2010 new crop prices and the need to replenish the large amount of nutrients withdrawn by the record crop this year, Chief Executive Officer Jim Prokopanko said in a statement.

The company is in the middle of a $5 billion campaign to boost its potash capacity by more than 5 million tons over the next 10 years.

Prokopanko has previously described the expansion as key to Mosaic's survival in the aggressive fertilizer sector.

Mosaic is part owner, together with Potash Corp

and Agrium Inc , of Canpotex, a lucrative overseas marketer of Canadian fertilizer.

For its fiscal first quarter, Mosaic posted earnings of $100.6 million, or 23 cents per share, compared with $1.18 billion, or $2.65 per share, in the year-ago period.

Revenue fell 66 percent to $1.46 billion.

Analysts had expected it to post earnings of 35 cents per share on revenues of $1.54 billion, according to Thomson Reuters I/B/E/S.

Sales of phosphate fell 69 percent and sales of potash dropped 66 percent.

Additionally, the average price for phosphate fell 73 percent and the average potash price dropped 22 percent.

In the company's overseas unit, sales slipped 53 percent.

Meanwhile, the Plymouth, Minnesota-based company said it will spend $32.4 million to address pollution concerns from the Environmental Protection Agency and Department of Justice.

Mosaic will install pollution monitors at a Louisiana plant and pay a fine to the EPA.

Shares of Mosaic were five cents higher in extended trading from their $45.96 close on the New York Stock Exchange.

(Reporting by Ernest Scheyder; Editing by Carol Bishopric and Tim Dobbyn)

Canada