GRAINS-Chicago soybeans extend gains on US-China trade optimism; corn, wheat firm

BEIJING, Oct 21 (Reuters) - Chicago soybean futures rose for a fifth straight session on Tuesday, as optimism over U.S.-China trade talks lifted hopes for renewed soybean purchases by the world's top buyer.

The most-active soybean contract on the Chicago Board of Trade (CBOT) Sv1 gained 0.29% to $10.34-3/4 per bushel by 0405 GMT, hitting a one-month high.

U.S. President Donald Trump said on Monday he expects to work out a fair trade deal with Chinese President Xi Jinping and that he wants Beijing to buy soybeans, ahead of his planned meeting with Xi in South Korea next week.

"The positives are that Trump and Xi are meeting, and that Trump has soybeans on his radar," StoneX Chief Commodities Economist Arlan Suderman said in a client note on Monday.

"It's yet to be seen whether the talk will result in concrete results, but traders want to be optimistic."

Corn Cv1 tracked soybeans higher, rising 0.18% to $4.24 a bushel, although gains were capped by expectations of a record U.S. crop.

Analysts surveyed by Reuters on average estimated that the U.S. soybean crop was 73% harvested by Sunday and the corn harvest was 59% complete.

Traders said the corn market also faced some pressure from tensions between the U.S. and Colombia, a major buyer of U.S. corn.

In Brazil, planting of the country's first-season corn crop was 51% complete in the key centre-south region, versus 48% a year earlier, agribusiness consultancy AgRural said on Monday.

Wheat Wv1 gained 0.15% to $5.05-1/2 a bushel but remained near five-year lows amid ample global supply.

Argentina and Australia are both expecting bumper harvests, while large supplies are also available in export markets from the Black Sea region.

Analysts have raised their estimates for Australia's wheat harvest, a Reuters poll showed on Monday.