Chicago soybean and corn futures fell for a second straight session on Wednesday as planting progress in the U.S. Midwest encouraged the market to give up more of last month's gains.
Wheat edged higher after steep losses on Tuesday which were triggered by forecasts of improved weather for the U.S. hard red winter wheat harvest.
The Chicago Board of Trade most-active soybean contract had fallen 0.56 percent to $10.72-3/4 a bushel by 1121 GMT, while corn dropped 0.4 percent to $4.03 a bushel.
Wheat added 0.4 percent to $4.66-1/2 a bushel. The contract steadied after slipping to a one-week low of $4.63 earlier in the session, when it added to Tuesday's 3.5 percent drop.
In its weekly crop progress report issued after the market closed on Tuesday, the U.S. Department of Agriculture pegged the condition of corn at 72 percent good to excellent, slightly ahead of market expectations.
U.S. farmers had finished planting 94 percent of the crop as of Sunday, the agency said, in line with expectations and slightly ahead of the five-year average.
Soybean plantings were 73 percent complete, the USDA said, sharply higher than 56 percent a week ago and above the average estimate of analysts polled by Reuters.
"While rain over the holiday weekend may have been a nuisance for fieldwork it does not appear to have slowed U.S. planting progress by all that much," said Tobin Gorey, director of agricultural strategy at Commonwealth Bank of Australia.
Soybean prices rallied strongly last month as concerns built up about rain losses to the harvest in Argentina, the world's biggest exporter of soymeal.
But the prospect that harvesting in Argentina will speed up in June due to forecasts for sunny weather, was now weighing on prices, traders said.
U.S. farmers have sold nearly double the usual amount of new-crop soybeans this spring, taking advantage of the recent rally, a trend that could depress premiums on the U.S. cash market.
Wheat remained under pressure from favorable harvest prospects in the United States which could add to large global inventories.
The USDA rated winter wheat crop 63 percent good to excellent, and spring wheat 79 percent good to excellent, with both scores above average market expectations.
In Europe, traders were monitoring heavy rain, including downpours in France that have caused localized flooding, although it was seen as too early to predict damage to wheat crop yields or quality ahead of the summer harvest.