CHICAGO (Oct 13): Chicago soybean futures jumped to a 2-1/2-month high on Thursday after the U.S. Department of Agriculture lowered its U.S. soybean yield estimate in a monthly report, bucking trade expectations for a slight increase.

Corn futures followed soybeans higher, rallying after front-month December set a contract low, while wheat futures retreated.

Chicago Board of Trade November soybeans settled up 26-3/4 cents at $9.92 per bushel after reaching $9.97-3/4, the contract's highest since Aug. 1.

CBOT December corn ended up 3 cents at $3.49 a bushel while December wheat fell 2-3/4 cents to $4.30-1/2 a bushel.

Soybean futures surged after the USDA cut its U.S. soy yield estimate to 49.5 bushels per acre (bpa), down from 49.9 in September and below all but one estimate in a Reuters poll.

"There's no question in my mind that the trade was expecting a bigger yield in both corn and beans. They probably could have tolerated an unchanged yield in beans, but to see it drop was quite a surprise," said Mike Zuzolo of Global Commodity Analytics.

Soybeans drew additional support from worries about below-normal rainfall in northern portions of Brazil's soy belt, where planting is under way.

Corn futures followed soybeans higher, rallying after the December contract fell to a life-of-contract low at $3.42-1/2.

Corn firmed despite the USDA raising its U.S. corn yield estimate to 171.8 bpa, above even the highest in a range of trade estimates.

"If it wasn't for soybeans making these big gains, corn would be on the negative side right now because there's nothing there to support it," said Karl Setzer, analyst with the MaxYield Cooperative.

CBOT wheat turned lower after following soybeans and corn higher. The CBOT December contract touched a six-week low, pressured by the USDA raising its U.S. and global 2017/18 wheat ending stocks forecasts.
   
"The international wheat numbers were devastating, with world production up 7 million tonnes, nearly equal to last year's production," ED&F Man Capital analyst Charlie Sernatinger wrote in a note to clients.