* Underlying H1 profit down 10 pct
* FY16 explosives sales volume forecast cut by 9 pct
* H1 dividend slashed to 20.5 cents from 40 cents
* Shares drop as much as 7 pct (Adds analyst, S&P comment)
By Sonali Paul
MELBOURNE, May 9 (Reuters) - Orica Ltd ORI.AX , the world's largest maker of mine explosives, slashed its forecast sales volumes and halved its dividend to weather a prolonged mining slump after reporting a 10-percent fall in half-year profit.
After predicting a year ago that 2015 would mark the trough for the mining downturn and earnings would rise modestly this year, the Australian company said on Monday that conditions had worsened sharply in January and February.
"Market conditions deteriorated more than we anticipated during the half, marked by increased volatility. It is expected that the market will remain challenged for the foreseeable future," Chief Executive Alberto Calderon said in a statement.
Orica's shares fell as much as 7 percent after the results were released in a broader market down just 0.1 percent.
Underlying profit for the six months to March dropped to A$190 million ($140 million) from A$211 million a year earlier, in line with a forecast of A$191 million from Macquarie.
The change in Orica's dividend policy was expected and the magnitude of the dividend cut just reflected that shift, said CLSA analyst Scott Hudson.
"Of more concern is the downgrade to the volume guidance," he said.
Ammonium nitrate sales volumes fell 8 percent to 1.71 million tonnes in the first half. The company said it now expects full-year volumes of 3.45 million tonnes, down from an earlier forecast of 3.8 million and down from last year.
The company's weaker forecast for this year was well below UBS estimates.
"(The) outlook for challenged markets for the foreseeable future is also likely to result in consensus downgrades beyond current year, in our view," UBS said in a note.
Orica sliced its interim dividend to 20.5 cents a share from 40 cents a year ago, and said it would pay out 40 to 70 percent of underlying earnings each year, looking to protect its investment-grade credit rating.
It also slashed planned capital spending for this year to A$320 million from an earlier forecast of around A$450 million.
Standard & Poor's said the more flexible dividend policy and cut in capital spending should help preserve Orica's 'BBB' rating.
($1 = 1.3569 Australian dollars)