U.S. soybean futures are poised for a lower start Thursday, succumbing to widespread selling of commodities, with slowing demand aiding the declines.

CBOT soybeans are called to open 15 cents to 20 cents lower.

In overnight trading, Chicago Board of Trade May soybean futures were down 0.9% at $13.21 3/4 a bushel, the most-active July contract was down 1.3% at $13.14 3/4, and new crop November futures were down 1.4% at $13.02.

Broad-based selling is expected to weigh on prices, as commodity traders reduce risk exposure in markets amid concerns that the pace of global economic growth is slowing, analysts said.

Softer prices are seen across precious metals, energy, and grain and oilseed futures, with a stronger U.S. dollar serving as a catalyst for the declines. A higher U.S. dollar is bearish for commodities as most raw materials are dollar-denominated, making them more expensive for foreign buyers to import.

Weaker outside markets should overwhelm any optimism from Wednesday's late price bounce that trimmed early declines, said Bryce Knorr, analyst with Farm Futures, an agricultural publication in a market note.

Slower demand will add to the defensive tone in the market. Sluggish weekly export sales and Wednesday's acknowledgment of weakening demand by federal forecasters, particularly with the market still holding historically big premiums, open the door for further selling.

The U.S. Department of Agriculture's weekly export sales report released Thursday said total soybean export sales were a net 62,300 metric tons for the week ended May 5, with 59,000 tons for delivery in the 2010-11 marketing year that ends Aug. 31. The sales included a cancellation of a sale for 49,000 tons to China. The soymeal sales totaled 61,000 metric tons, below expectations of 75,000 to 125,000 tons, and soyoil export sales totaled 2,000 tons, near the low end of analyst's expectations for sales in a range of zero to 10,000 tons.

China, the leading importer of U.S. and global soybeans, has slowed its purchasing of late, as China's soybean demand is reportedly sluggish with port inventories high and supplies at crushing plants at comfortable levels.

Ongoing uncertainty about 2011 plantings, with the threat of delayed seeding in the eastern Midwest possibly shifting some intended corn plantings to soybeans, will provide pressure to reduce some premium in prices as well.

However, traders were encouraged by soybeans' ability to withstand limit down pressure from corn futures Wednesday, a sign that there is price support beneath the market.

Despite higher-than-expected supply forecasts from federal forecasters, stocks remain historically tight, and analysts see little relief from low soybean supplies next year.

The tightness of the inventory forecast leaves hardly any breathing room for any threats to 2011 plantings or crop production, said Bill Nelson, analyst with Doane Advisory Service.