The US Agriculture Department lowered its outlook for the corn harvest by less than most analysts were expecting on Thursday, with yield expectations seen as robust after good weather bolstered crop development during September.

Crumbling demand for corn due to ample global supplies will also keep US stocks plentiful, the government World Agriculture Supply and Demand Estimates report showed.

Chicago Board of Trade corn futures fell 3.5 percent.

"There's way more corn than we thought there was going to be," said Tomm Pfitzenmaier, an analyst for Summit Commodity Brokerage. "It just makes it tough going for the corn market given the demand we've got - or don't have."

The government also cut its outlook for soyabean production below the average of market expectations, with forecasts for harvested acreage and yields less than in the outlook issued a month ago.

The most-actively traded Chicago Board of Trade November soyabean futures contract was up 3-3/4 cents at $9.27-1/2 a bushel.

The USDA pegged the 2019/20 US corn crop at 13.779 billion bushels, based on an average yield of 168.4 bushels per acre. Soyabean production was seen at 3.55 billion bushels, with average yields of 46.9 bushels per acre.

Some analysts said they expected the corn view to come down in the next report, with a storm hitting western and northern stretches of the Midwest seen causing some damage to the crop in coming days.

Farmers have disparaged the USDA's harvest estimates for being too high throughout the growing season, saying the government's forecasts do not reflect the adverse weather the crop has faced since planting.

Analysts had forecast corn production of 13.684 billion bushels, corn yields of 167.5 bushels per acre, soyabean production of 3.583 billion bushels and soyabean yields of 47.3 bushels per acre, based on the average of estimates in a Reuters poll.

A month ago, the corn harvest was seen at 13.799 billion bushels on yields of 168.2 bushels per acre. USDA's soyabean harvest forecast in September was 3.633 billion bushels, based on an average yield of 47.9 bushels per acre.

The USDA lowered its 2019/20 corn ending stocks projection by 11.9 percent to 1.929 billion bushels, mostly due to lower carryover stocks, near the high end of analysts' estimates.

On the demand front, it cut its export projections for corn by 150 million bushels to 1.900 billion bushels and ethanol demand view by 50 million bushels to 5.400 billion bushels.