Chicago grain and soybean futures were little changed during European trading on Tuesday as investors awaited a monthly crop outlook from the U.S. government for further clues on global supply prospects.

Soybeans gave up early gains linked to concerns over hot weather forecasts and expectations that the U.S. Department of Agriculture will trim U.S. soy stocks in its closely watched supply and demand report.

Corn was flat and wheat edged down in position squaring ahead of the USDA data due at 1600 GMT.

The Chicago Board of Trade most-active soybean contract was down 0.1 percent at $10.54-1/4 by 1210 GMT, reversing a small earlier rise.

Corn also ticked down 0.1 percent, to $3.55 a bushel, while wheat eased 0.2 percent to $4.29-1/2 a bushel.

Analysts surveyed by Reuters expected the USDA to raise its forecast of 2015/16 and 2016/17 U.S. corn ending stocks, while lowering its forecast for 2015/16 U.S. soybean stocks.

While U.S. corn inventories are expected to balloon above 2 billion bushels by the end of the 2016/17 marketing year, soybean stocks should be much tighter due to export demand from China and crop problems in South America.

"The current uncertainty surrounding the longer term weather outlook is allowing soybeans to hold on to gains," said Madeleine Donlan, agricultural commodities analyst at Commonwealth Bank of Australia. "The soybean market has less of an inventory buffer following large losses to South American crops earlier in the year."

In a separate weekly crop report on Monday, the USDA rated 76 percent of the U.S. corn crop in good to excellent condition, up from 75 percent a week earlier, and 71 percent of the U.S. soybean crop as good/excellent, up from 70 percent.

But the soybean market has been wary of any signs of hot, dry summer weather that could stress soybean crops and potentially further tighten supplies in the United States and globally after harvest losses in South America.

U.S. wheat has been recovering from a 10-year low hit last week amid strong harvest yields in the United States and the Black Sea region.

A tender on Tuesday from Egypt, the world's biggest wheat importer, could add to pressure on wheat if it shows Black Sea origins to be much cheaper than U.S. and western European wheat.