By Rod Nickel and Amrutha Gayathri

(Reuters) - Miners that produce a diverse commodity mix may be willing to part with fertilizer assets, creating buying opportunities for producers of potash and phosphate, Mosaic Co <MOS.N> Chief Executive Joc O'Rourke said on Tuesday.

Profits of fertilizer producers have tumbled because of falling prices, weak currencies in importing countries such as Brazil and excessive supplies.

Mosaic, the world's largest producer of finished phosphate products, reported lower-than-expected adjusted profit on Tuesday as crop nutrient prices remained weak. But the company joined larger rival Potash Corp of Saskatchewan Inc <POT.TO> in saying that the worst was over.

Bigger miners may be unwilling to wait for recovery, O'Rourke said in an interview. Some of them question whether fertilizer fits their core portfolios as they look to sell assets and pay down debt, he said.

"We think some of these opportunities might come to fruition, and if they do, they may add some long-term value to us,” O'Rourke said.

Reuters reported in June that Plymouth, Minnesota-based Mosaic was in talks to buy Vale SA's <VALE5.SA> fertilizer unit, in a renewed push to grow in South America and Africa.

O'Rourke declined to comment on any talks with Vale.

Mosaic shares jumped 2.8 percent at $27.37, after executives told analysts that better demand was ahead in the second half.

Mosaic expects sales volume and prices of phosphate and potash to rise in the current quarter from the second quarter.

Potash volumes would be helped by a long-overdue 2016 sales agreement between Chinese buyers and Canpotex Ltd, the offshore sales arm of North America's Mosaic, Potash Corp, and Agrium Inc <AGU.TO>.

Some rivals have already settled at a sharply lower price of $219 per tonne, and the focus of Canpotex negotiations now is on volume, O'Rourke said.

"Once the price gets set, that is the price, and your participation choice is how much volume" to commit, O'Rourke said.

Mosaic reported a net loss of $10.2 million, or 3 cents per share, for the second quarter, compared with a profit of $390.6 million, or $1.08 per share, a year earlier.

Excluding certain items, profit was 6 cents per share, compared with analysts' average estimate of 12 cents, according to Thomson Reuters I/B/E/S.

Revenue fell 32.7 percent to $1.67 billion.

Mosaic said it would slash its 2016 capital budget and cut other expenses to preserve cash. The company idled production in July at its Colonsay, Saskatchewan potash mine for the rest of 2016.

(Reporting by Amrutha Gayathri in Bengaluru and Rod Nickel in Winnipeg, Manitoba; Editing by Shounak Dasgupta and Grant McCool)