Traders also were positioning ahead of Friday's last trading day for Chicago Board of Trade May corn options, with large open interest in calls at the strike prices of $4.90 and $5.00 per bushel.
Concerns that rains forecast in the Corn Belt in the next few days capped losses. The slow start to the planting season in the United States bolstered prices earlier in the session.
The US Agriculture Department said old-crop export sales of corn last week totaled 618,900 tonnes, within analyst estimates ranging from 500,000 to 800,000 tonnes.