* Russian export tax supports U.S. wheat

* Chicago soybeans ease on South American rain, palm oil slide

* Corn follows soybeans, supported as Ukraine debates export cap

CHICAGO, Jan 19 (Reuters) - Chicago soybean futures slid on Tuesday as rain across South America strengthened crop prospects and bolstered the global supply outlook, traders said.

Corn followed soybeans lower, but was supported by strong export demand and possible export limits in Ukraine.

Wheat futures hovered above even, bolstered by an export tax in top-producer Russia.

The most-active soybean contract on the Chicago Board of Trade (CBOT) fell 24-1/2 cents to $13.92-1/4 per bushel by 10:58 a.m. (1658 GMT).

CBOT corn slipped 4-1/4 cents to $5.26-3/4 per bushel, while wheat shed 2 cents to $6.73-1/2 per bushel.

Rains across much of Brazil's crop-growing regions bolstered parched crops, as the country slowly begins its soybean harvest.

"We do see a wetter pattern for South American weather next week," said Dan Anderson, broker at ED&F Man Capital.

Falling palm oil futures further weighed on soybeans, while the U.S. Department of Agriculture's announcement of fresh export sales of 132,000 tonnes of soybeans to China for shipment in the 2021/2022 marketing year did little to strengthen the market.

Corn fell after gaining early, as discussions in Ukraine about possible export limits offered support.

The USDA reported private U.S. corn sales totaling 128,000 tonnes to Japan and 100,000 tonnes to Israel, both for shipment in the 2020/21 marketing year.

Top importer China bought a record 11.3 million tonnes of imported corn last year, according to General Administration of Customs data.

Wheat, too, benefited from China's increased imports, with a record 8.38 million tonnes of wheat imported in 2020.

Wheat climbed early, supported by Russia's additional wheat export tax of 50 euros a tonne from March 1 to June 30, adding to the 25 euro levy from Feb. 15, aimed at cooling food inflation.

"It looks like a rush for these foreign countries to try and buy wheat before that tax goes on," said Don Roose, president of U.S. Commodities. (Reporting by Christopher Walljasper; additional reporting by Gus Trompiz in Paris and Naveen Thukral in Singapore; Editing by Dan Grebler)