Chicago corn futures edged lower on Tuesday, consolidating below a decade high reached earlier, as traders assessed risks to global supply from the war in Ukraine and a slow start to planting in the United States. Wheat also turned lower while soybeans gave up most of their gains as weakness in wider financial markets, where the focus was on expected U.S. interest rate hikes, countered fundamental support for grains.

The most-active corn contract on the Chicago Board of Trade (CBOT) was down 0.2% at $8.05-3/4 a bushel, after earlier reaching its highest since September 2012 at $8.14. U.S. corn planting was 4% complete as of Sunday, below the five-year average of 6%, the U.S. Department of Agriculture said in a report issued after CBOT grain markets closed on Monday, and the 5% forecast in a Reuters poll of analysts.

The market is particularly sensitive to any potential setback in the U.S. corn crop as Russia's invasion of Ukraine has stalled massive Ukrainian corn exports.

Cool, wet weather has hampered early field work in the U.S. Midwest. CBOT wheat was down 0.4% at $11.24 a bushel. The USDA's crop report also underscored drought risks to the U.S. wheat crop that could exacerbate a shortfall in supply from Ukraine. The USDA rated 30% of U.S. winter wheat in good-to-excellent condition, down two percentage points from a week ago.

The rating was below an average of analyst expectations and the lowest for this time of year since 1996.

"The water deficit on the large wheat plains in the south of the country continues and could therefore compromise the yields of the future crop," consultancy Agritel said. CBOT soybeans was up 0.3% at $17.19-3/4 a bushel, underpinned by strong domestic and export demand for U.S. beans.

The USDA's first estimate of soybean progress for 2022 showed planting as 1% complete, matching the average analyst expectation but behind the five-year average of 2%. 

(Reporting by Gus Trompiz in Paris and Enrico Dela Cruz in Manila; Editing by Uttaresh.V, Sherry Jacob-Phillips and Barbara Lewis)