GRAINS-U.S. soybean futures reach highest price since June 2018 on China trade hopes

(New throughout, updates prices and market activity to close; adds U.S. export estimates, SovEcon forecast for Russian wheat exports)

* Traders await details on Chinese buying

* Favorable Brazil crop weather limits CBOT soy

* Firming global prices underpin CBOT wheat

CHICAGO, Dec 26 (Reuters) - The most actively traded U.S. soybean futures contract rose on Thursday, touching its highest price since June 2018 on optimism about U.S.-China trade.

Traders and farmers hope China, the world’s biggest soybean importer, will ramp up U.S. purchases following a recently struck Phase 1 trade deal, which includes a commitment by Beijing to buy more American farm products. China is in close touch with Washington on signing the deal, the country’s commerce ministry said.

Details about China’s buying remain unknown, and analysts doubt its purchases will reach U.S. projections for $40 billion to $50 billion.

“Who wants to be short right now until we know the details of the Phase 1 trade deal?” said Arlan Suderman, chief commodities economist for broker INTL FCStone.

Chicago Board of Trade (CBOT) March soybeans ended up 1-3/4 cents at $9.46-1/2 a bushel. The contract, which has replaced January as the most actively traded month, set a session high of $9.49, highest for a most-active contract since June 13, 2018.

Traders were adjusting positions ahead of year end. Strength in Malaysian palm oil also helped support soy futures, analysts said. CBOT March soybean oil rose 0.51 cent to 34.67 cents per lb.

Advances were constrained by generally favourable crop weather in South America, which competes with the United States for export business. Brazil’s soybean exports typically accelerate early in the new year as farmers harvest crops, taking business away from the United States. During the trade war, China bought soy from Brazil instead of the United States.

“Cheaper South American beans, nearly ideal weather in South America, along with an expected drop-off in export demand are going to limit rallies in beans,” said Tomm Pfitzenmaier, analyst for Summit Commodity Brokerage in Iowa.

The U.S. Department of Agriculture on Friday is expected to report U.S. soybean export sales totalled 700,000 tonnes to 1.55 million tonnes last week, according to analysts surveyed by Reuters. Weekly export sales are estimated to be 500,000 to 1.3 million tonnes for corn and 200,000 to 900,000 tonnes for wheat.

Most-active corn edged up 1 cent at $3.88-1/2 a bushel, and wheat rose 8 cents to $5.49 a bushel at the CBOT.

Technical buying and firming global cash prices helped support wheat futures, analysts said.

Russian agricultural consultancy SovEcon said the market was overestimating the wheat supply from Russia, the world’s top exporter of the grain. (Reporting by Tom Polansek in Chicago; Editing by Richard Chang and David Gregorio)