CHICAGO: Chicago soybean futures gained on Tuesday as traders assessed the impact of a lower-than-expected U.S. plantings forecast and a rain-delayed harvest in Brazil on ever-tightening supplies of the oilseed.

Corn futures were mixed, with old-crop contracts rising slightly as investors adjusted positions ahead of a monthly U.S. Department of Agriculture world supply and demand report on Friday that could show a further reduction in supplies.

Wheat futures slumped, despite concerns about dryness in growing areas in the U.S. Northern Plains.

The most-active soybean futures on the Chicago Board of Trade were up 6-1/4 cents at $14.19 per bushel by 12:00 p.m. (1800 GMT).

CBOT corn added 1-1/2 cents to $5.54-3/4 per bushel, while CBOT wheat slid 2 cents to $6.16 per bushel.

Nearby soybean contracts gained as the harvest picture in South America comes into focus, with traders anticipating reductions due to excessive rains in Brazil and a lack of moisture in Argentina.

New-crop CBOT soybean contracts found support from concerns that any U.S. weather issues, coupled with lower-than-expected soybean planting acres reported last week by the USDA, could result in another year of tight soybean supplies.

"There are a lot of areas with soil moistures that are very inadequate right now," said Dan Smith, senior risk manager at Top Third Ag Marketing.

Corn futures also drew support from South America, after rain delays slowed second-crop corn plantings.

"They planted about a month late. They're going into their dry season during the pollination season. That could really clip their yields," said Smith.

For wheat, analysts said there are concerns that persistent dryness across North and South Dakota could impact spring wheat planting.

"Spring wheat could lead the charge higher, if we continue to be worried about weather conditions up in the Northern Plains," said Ted Seifried, vice president at Zaner Group.

MGEX May spring wheat was up 3 cents at $6.10-1/2 a bushel.