U.S. corn futures climbed for a fourth straight session on Tuesday on technical and speculative buying and amid concerns over tight supplies of the feed grain.
Wheat futures followed corn higher while soybeans drifted lower in light trading, under pressure from a lack of fresh buying by top importer China.
"It's all about corn and the tight stocks. Cash is strong and there will be a squeeze in May and July because of that -- we will be short of corn," said Joe Bedore, CBOT floor manager for trade house INTL FCStone.
Traders continued to spread positions, buying corn and selling soybeans, which helped to send actively traded May corn to its highest level in a month.
The monthly supply/demand report from the U.S. Department of Agriculture also helped.
"The trade is feeling comfortable after the USDA report last week, given yesterday's export inspections and given news of more new-crop corn sales to China, in continuing to unwind the bean/corn spreads," said Mike Zuzolo, president of Global Commodity Analytics.
USDA kept its end-of-season corn stocks forecast steady at 632 million bushels, the smallest in 17 years and a bare three-week supply.
Private Chinese importers seized upon a dip in prices and have bought about 600,000 tonnes of new-crop U.S. corn since February, traders said.
May corn on the Chicago Board of Trade (CBOT) climbed three cents to $7.14-1/4 per bushel, after peaking at $7.17-3/4, its highest since Feb. 8 (all figures US$).
The contract found support at its 50-day moving average around $7.08-1/4 but failed to break through resistance at its 200-day moving average of $7.20-1/4.
CBOT May soybeans fell 10-3/4 cents to $14.68-3/4 per bushel.
Port congestion and loading delays in Brazil limited declines in soybeans as exports from the U.S. were expected to fill near-term global demand.
The market was awaiting news from South America on whether a port strike in Brazil, scheduled to begin next Tuesday (March 19), would severely disrupt export shipments.
CBOT May wheat rose for a fourth straight session, adding 3-1/2 cents to $7.03-1/2 a bushel. But the contract held within the previous day's trading range and failed to break chart resistance at its 14-day moving average of around $7.06-1/2.
-- Karl Plume writes for Reuters from Chicago. Additional reporting for Reuters by Sam Nelson.