* Chicago corn futures rise after four days of losses

* U.S. harvest pressure keeps a lid on prices

* Lower prices, South American dryness may support prices

* Sovecon raises forecast for Russia's 2021 wheat crop

SINGAPORE, Sept 22 (Reuters) - Chicago corn futures edged higher on Wednesday, although gains were capped by signs of ample global supplies as U.S. farmers race to finish harvesting the crop.

Wheat gained ground after three days of decline while soybeans were largely unchanged.

"The market is focused on building seasonal pressure with the U.S. harvest," said Tobin Gorey, director of agricultural strategy at Commonwealth Bank of Australia.

"Such a decline though stands a greater chance of finding significant buying. Dry South American crop regions are an issue that may help arrest the decline."

The most-active corn contract on the Chicago Board Of Trade (CBOT) added 0.2% to $5.17-3/4 a bushel as of 0255 GMT, having closed 0.9% lower in the previous session when prices hit their weakest since Sept. 14.

Wheat was up 0.4% at $6.92-3/4 a bushel and soybeans were little changed at $12.73-3/4 a bushel.

The U.S. Department of Agriculture (USDA) said after Monday's market close that the U.S. corn harvest was 10% complete, ahead of the five-year average of 9% for this time of the year.

The USDA rated 59% of the U.S. corn crop in good-to-excellent condition, up 1 percentage point from the previous week, while also raising its soybean good-to-excellent score by 1 point to 58%. Analysts on average had expected no change to either ratings.

The agency's data on Monday showed corn export inspections were down 48% from the same week a year ago, while soybean inspections were down 80%.

The wheat market is under pressure from expectations of higher output in Russia.

Russian agriculture consultancy Sovecon said on Tuesday it had raised its forecast for the country's 2021 wheat crop by 200,000 tonnes to 75.6 million tonnes due to good yields in Siberia.

Russia is the world's largest wheat exporter, supplying it mainly to Africa, the Middle East and Asia. Its crop, dominated by winter wheat, is expected to be lower than in 2020, when it harvested 85.9 million tonnes, due to dry weather.

Indian farmers are expected to harvest a record 150.50 million tonnes of grains from summer-sown crops in the crop year to June 2022, the government said on Tuesday, against 149.56 million tonnes gathered in the previous year.

Commodity funds were net buyers of CBOT soybeans, soymeal and soyoil futures contracts on Tuesday, and net sellers of CBOT corn and wheat, traders said. (Reporting by Naveen Thukral; Editing by Devika Syamnath)