GRAINS-Chinese buying and harvest pressure weigh on soybean futures

By Naveen Thukral and Sybille de La Hamaide

SINGAPORE/PARIS, Sept 26 (Reuters) - Chicago soybean futures fell on Friday, poised for a second weekly loss due to large Chinese purchases of Argentine soybeans at the expense of U.S. supplies and seasonal pressure from the North American harvest.

Wheat and corn prices also fell on bearish sentiment in the agricultural markets.

The most-active soybean contract on the Chicago Board of Trade Sv1 fell 0.1% to $10.11 a bushel, as of 1115 GMT, with prices down 1.4% this week.

Wheat Wv1 lost 0.3% to $5.24-1/4 a bushel and corn Cv1 fell 0.2% to $4.25 a bushel. Both wheat and corn are set to end the week marginally higher, having dropped last week.

China's absence from the U.S. soybean market amid a Washington-Beijing trade war was keeping a lid on prices.

"China's purchases of Argentinian soybeans have put further downward pressure on Chicago futures," said one oilseed trader in Singapore. "The global soybean market is well supplied as U.S. harvest is gaining momentum."

Around 40 Argentine soybean cargoes were registered for export in November and December during this week's export tax suspension, mostly headed to China, two traders told Reuters, in purchases that directly eat into the prime U.S. marketing season.

A total of 2.66 million tons of soybeans were registered for November and December, accounting for more than 50% of the 5.1 million tons of total volume booked for all months cited by Argentine officials during the tax-free window, they said.

The buying frenzy by Chinese importers this week was a fresh blow for U.S. soybean farmers, who have been shut out of exports to top market China during the current harvest season as trade war tariffs make their beans prohibitively expensive for Chinese buyers.

The advancing U.S. corn and soy harvests have put some supply pressure on prices, though doubts over the size of corn yields have lent support to that market.

The U.S. Department of Agriculture reported net U.S. soybean export sales were 724,500 tons for 2025/26 in the week that ended on September 18. Analysts expected 600,000 to 1.6 million tons.

Weekly U.S. corn export sales of 1.9 million tons topped analysts' estimates for 1 million to 1.8 million.

Ample world supplies kept a lid on the wheat market.

Australia is on track to reap its third-biggest wheat harvest and its largest-ever barley crop this year, according to a poll of analysts, many of whom have raised their estimates in recent weeks thanks to favourable crop conditions.