Nov 14 (Reuters) - Singapore commodities firm Olam International on Monday posted a 15 percent rise in its first-quarter net profit as an increase in overall sales volume offset a drop in earnings from cotton.

Olam booked S$34.2 million ($26.6 million) in net profit in the three months ended Sept 30, up from S$29.7 million a year ago.

The company said that very high volatility in cotton prices and weakening demand for the commodity due to macro-economic uncertainties had reduced net contribution from cotton, but the price swings seem to be stabilizing.

"We believe that the unprecedented volatility seen in the cotton markets in the last cropping season seem to have now stabilized as we enter the new cropping season," it said.

Analysts had been concerned that Olam, one of the world's largest cotton traders, would be caught up by defaults involving cotton players in the United States, which partly contributed to rival commodities firm Noble Group's first quarterly loss in 14 years.

Olam trades about 20 different commodities ranging from almonds and cashews to cocoa and coffee. ($1 = 1.285 Singapore Dollars)