Chicago soybeans rose for a second session on Thursday, hitting their highest since early December with prices underpinned by a weak dollar and expectations that U.S. farmers will plant less beans in the upcoming season.

Wheat rose, rebounding from losses of 1.4 percent on Wednesday, although gains were capped by a lack of demand for pricy U.S. wheat.

Chicago Board of Trade's most-active soybean contract gained as much as 0.5 percent to $8.99 a bushel, its highest since Dec. 7.

Wheat climbed 0.3 percent to $4.72-1/4 a bushel and corn added 0.2 percent to $3.69 a bushel.

"The market took support from suggestions that U.S. farmers may favor planting corn over soybeans more heavily than expected," said Tobin Gorey, director of agricultural strategy at Commonwealth Bank of Australia in Sydney.

"Even so, the prospect of improving South American weather kept a lid on the market's gains."

U.S. farmers will expand their plantings of corn by nearly 3 percent in 2016 while scaling back slightly on soybeans, according to a survey of growers released on Wednesday by Illinois-based research and brokerage firm Allendale Inc.

Allendale's survey of farmers in 25 U.S. states said plantings of corn would increase to 90.431 million acres from 87.999 million in 2015, with soybean acreage dipping to 82.575 million from 82.650 million.

U.S. farmers are due to start planting corn and soybeans next month. Back-to-back record global production of soybeans since 2011/12 has weighed on prices of the oilseed which is down around 50 percent from its 2012 peak of $17.89 a bushel.

Grain markets were supported by a weaker U.S. dollar after the U.S. Federal Reserve statement said moderate economic growth and job gains would allow it to resume tightening monetary policy this year. A weak dollar makes U.S. supplies less expensive for overseas buyers.

U.S. wheat shipments continue to face headwinds from cheaper supplies in Europe and the Black Sea region.

Egypt, the world's top buyer of wheat, said it bought 240,000 tonnes in a tender from France, Romania and Ukraine.

Temperatures are forecast to drop below freezing late this week in much of the southern Plains, but not low enough to cause significant damage, meteorologists said.

Commodity funds sold an estimated net 4,000 CBOT wheat contracts on Wednesday, trade sources said. The funds were also net sellers of 1,000 corn contracts and net buyers of 3,000 soybean contracts, they said.