U.S. soybean futures fell on Friday along with crude oil prices, pressured by weaker-than-expected economic data from China, traders said.
The decline came despite the U.S. Agriculture Department's announcement of another sale of U.S. soy to the world's top buyer of the oilseed.
Wheat futures firmed as bargain buyers entered the market with prices trending near eight-month lows. Corn also edged higher, rebounding from an early decline, with tight cash supplies contributing to the gains.
Soybeans faced further pressure from rising expectations for the crop being harvested in South America.
CBOT May soybeans settled down 8-3/4 cents at $14.43-1/2 a bushel (all figures US$). The spot contract rose 0.2 per cent this week.
Private forecaster Informa Economics raised its estimate of the soybean crop in Brazil to 84.5 million tonnes from 84 million, trade sources said. Its forecast for soybean harvest of 51 million tonnes in Argentina was unchanged from its late February outlook.
CBOT May wheat was up six cents at $7.20 a bushel, while CBOT May corn rose five cents to $7.08-1/2 bushel.
Corn futures were up 4.9 per cent for the week, snapping a streak of three straight losing weeks. It was their biggest weekly gain since July.
Some commercial buyers were buying the March corn contract, which is in the delivery period, to try to source physical supplies through the futures market, said Ted Seifried, senior market analyst at the Zaner Group. Tightening basis levels on the cash market and slow farmer selling have made it hard for commercial operations to boost corn supplies.
Wheat futures were down 0.2 per cent for the week and have shed 9.9 per cent of their value during a six-week losing streak.
Rising demand for U.S. supplies was helping keep wheat firm on Friday. Saudi Arabia's state grains agency tendered to buy 550,000 tonnes of wheat earlier this week and traders said there was hope that the U.S. will pick up at least part of that business.
The dollar index hit a six-month high on Friday as weak euro zone data highlighted a growing economic disparity with the U.S.
Growth in Chinese factories cooled in February to a five-month low after domestic and foreign demand slackened, an official government survey showed on Friday, missing market forecasts.
"China is the world's largest soybean consumer, so further signs of an economic slowdown are going to dampen the demand for the commodity," said Ker Chung Yang, senior investment analyst at Phillip Futures in Singapore.
Private exporters reported the sale of 120,000 tonnes of U.S. soybeans to China for delivery during the 2013-14 marketing year, USDA said early Friday. USDA has reported four soybean sales to China, totalling 483,000 tonnes this week.
The U.S. grains complex has been buoyed by demand for exports and lengthy vessel loading delays in Brazil, which has prompted China to cancel soy cargoes ordered from Brazil and buy from the U.S. instead.
"The focus in the market... has turned back to old-crop tightness and the stronger outlook for grain exports from the United States," Rabobank analyst Nick Higgins said.
-- Mark Weinraub is a Reuters correspondent covering the grain futures markets from Chicago. Additional reporting for Reuters by Nigel Hunt and Natalie Huet in London, Lewa Pardomuan in Singapore and Sybille de La Hamaide in Paris.