By Renee Hickman
CHICAGO, May 29 (Reuters) - Chicago corn futures fell on Thursday as beneficial weather patterns moved through growing areas, analysts said.
Cheap South American crops also weighed on U.S. commodity prices.
The most active soybean contract on the Chicago Board of Trade (CBOT) Sv1 firmed 3 cents at $10.51-1/2 a bushel at 1:12 p.m. CST (1812 GMT).
Most active corn Cv1 fell 4 cents to $4.47 per bushel.
Drier weather is expected across the central U.S. through the weekend, but widespread rain is forecast for the six to 10-day period, according to Commodity Weather Group.
A benign mix of rain and sun in store for the corn crop in the coming weeks pressured futures on Thursday, said Randy Place, analyst at the Hightower Report.
"We are starting to see that South American prices are undercutting U.S. corn export prices now that Argentina's harvest is moving forward and Brazil's safrinha crop harvest is just now starting," Place said.
U.S. weather also weighed on soybean futures.
Wheat futures firmed slightly on Thursday, with rains forecast for the U.S. Plains offsetting support from lower-than-expected U.S. Department of Agriculture crop ratings earlier in the week, said Place.
Most active wheat Wv1 rose 3-3/4 cents to $5.34 a bushel.
The U.S. dollar turned lower on Thursday, giving wheat a lift as investors monitored U.S. President Donald Trump's appeal against a U.S. trade court decision on Wednesday that blocked most of his proposed tariffs.
A weaker dollar makes U.S. farm exports more competitive for buyers with other currencies.
"There's such uncertainty on trade that the market can't really get moving in either direction very far," Place said.