CHICAGO: Chicago soyabean futures fell for a third day on Friday, pressured by harvest activity and strong planting progress in South America that may open up export competition by mid-January, analysts said.
Corn also eased from harvest pressure, while wheat stepped back after reaching a nine-year high earlier in the week.
Corn and soyabeans were capped by expectations that the USDA will increase its US harvest forecasts.
The Chicago Board of Trade's (CBOT) most active soyabean contract fell 17-1/4 cents to $12.05-1/2 a bushel, ending the week down 3.52%, the biggest weekly drop since the week ended Aug. 20.
CBOT corn ended 6-1/4 cents lower at $5.53 a bushel, while wheat lost 7-1/4 cents to $7.66-1/2 a bushel.
After rain delays pushed back corn and soyabean harvests, this week has offered a clear window for field work, said John Zanker, market analyst at Risk Management Commodities.
"We should get most of the beans out by the middle of next week, when it starts to rain again," he said. "We're starting to see some lines at the elevators that we weren't seeing earlier, as we have run out of room on the farm."
South American planting progress also pressured soyabeans, as Brazil looks to finish seeding ahead of schedule, pushing up the potential harvest and shrinking the US export window.
"If their season goes according to plan, they're going to have new crop available in mid-late January. Then we're done," said Tom Fritz, commodity broker with EFG Group.
Corn also suffered from harvest pressure, but remained underpinned by rising fertilizer prices that could affect farmers' planting decisions next spring.
"It's not a stretch to think we're going to cut corn acres," said Zanker. "With input costs rising sharply, and competition from not only soyabeans, but cotton, oats and sorghum, it's going to be tough to get the acreage we need.
Wheat remained near nine-year highs, supported by global supply concerns as dry growing conditions in Russia and Ukraine threatened recently sown winter crops after poor spring harvests this year.
Global wheat demand continues to be strong with higher-than-expected purchases by top buyers.
Some traders however see a possible correction as expected crops in Argentina and Australia bolster supply, while late corn harvests in the Northern Hemisphere meet livestock feed needs.
Rain in Argentina over the past week helped developing 2021/2022 wheat crops, the Buenos Aires Grains Exchange said on Thursday.
However there was concern heavy rain could damage Australia's wheat crop, bringing the risk of knocking over maturing wheat crops in the eastern third of the country's wheat belt, Commodity Weather Group said in a note.