Soybeans rise on tight near-term supply; corn, wheat steady

* Delayed arrival of Brazil crop adds to global supply tension

* Wheat edges up on dryness concerns

* Soybeans add as tight supply worries extend into new crop

CHICAGO, April 6 (Reuters) - 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 ended 6 cents higher at $14.18-3/4 per bushel.

CBOT corn added 1 cent to $5.54-1/4 per bushel, while CBOT wheat slid 2-1/2 cents to $6.15-1/2 per bushel.

Nearby soybean contracts gained, even as agribusiness consultancy Agroconsult reported Brazilian farmers will harvest an estimated 137.1 million tonnes of soybeans in the 2020/2021 cycle, a record volume despite weather-related challenges.

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 drew support as rain delays to Brazil's second-crop corn plantings could reduce the country's harvest 4.5 million tonnes to 78.3 million tonnes, Agroconsult said.

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 ended 3-1/2 cents higher at $6.11 per bushel. (Reporting by Christopher Walljasper in Chicago Additional reporting by Gus Trompiz in Paris and Colin Packham in Canberra Editing by Dan Grebler and Matthew Lewis)