U.S. soybean futures are expected to start higher Thursday, driven by ongoing risks to yield and acreage potential amid delayed plantings in the eastern Midwest and northern Plains.

Chicago Board of Trade soybeans are called to open 8 cents to 10 cents higher.

In overnight trading, CBOT July soybeans were up 0.7% at $13.86, and new crop November futures were up 0.7% at $13.70.

Mounting concerns that delayed plantings may produce reduced yields or smaller acreage if farmers opt for preventive planting insurance the longer rains keep farmers out of fields are underpinning prices, Doane Advisory Service said in a market note.

Spillover support from neighboring grain futures and concerns that Midwest weather will shift to a stressful heat pattern next week added uncertainty to buoy prices as well, Doane added in the note.

The Telvent DTN weather forecast said another round of rain and storms will continue to delay spring planting through eastern and southern growing areas of the U.S. Midwest. The longer range maps continue to feature an upper level ridge in the east and south during the early part of the 6-10 day period, which will help to dry out fields and improve conditions for planting and early development, Telvent added.

Traders are also expected to look beyond the soybean market to the outside markets for guidance, with a lower U.S. dollar index adding further support. A lower U.S. dollar is supportive for commodities as most raw materials are dollar-denominated, making it less expensive for foreign buyers to import.

However, prices are expected to continue to hold within recent trading ranges as slow export and domestic demand continue to limit upside movement in prices. The decline in demand was confirmed in government reports on exports and crush Thursday. Freshly harvested South American supplies have increased competition for global soybeans and soy product exports, with cheaper Brazilian and Argentina supplies an attractive alternative to U.S. supplies.

The Census Bureau reported soybeans crushed in April totaled 127.981 million bushels, below the average of trade estimate at 129.3 million and down from March's crush rate of 140.3 million. Soymeal inventories or stocks climbed to 442,876 short tons from 325,136 in March. Soyoil stocks slipped to 3.318 billion pounds from 3.409 billion in March, but were above the average of trade estimates at 3,282 billion.

The U.S. Department of Agriculture's weekly export sales report released Thursday said soybean export sales for delivery in the 2010-11 marketing year that ends Aug. 31 were a net 163,200 metric tons for the week ended May 19. Soymeal sales totaled 142,800 metric tons, above expectations of 25,000 to 100,000 tons, and soyoil export sales totaled 500 tons, near the low end of analyst's expectations for sales in a range of zero to 10,000 tons.