US farm officials sided with commentators, such as Goldman Sachs, forecasting a rebound in soybean prices rather than those foreseeing a further easing, predicting a boost to values once harvest ends.

Investors have largely diverged between those foreseeing that Chicago soybean futures will recover much of the $3 a bushel they have lost since reaching a record high early in September, and those, such as Credit Suisse, seeing the drop as more permanent, with large South American crops scheduled for early 2013.

And US Department of Agriculture officials acknowledged, in follow-up comments to Thursday's Wasde crop report, the boost to ideas for world soybean supplies offered by their upgrade in the briefing to their forecast for the US crop.

"Although Midwestern pod counts this year are still generally below average, an extended growing season seems to have aided filling of those pods and their bean weights," the USDA staff said.

"An improved outlook for the US supply of soybeans this year would help ease the global market's transition between crops in the US and South America."

'Upward momentum'

However, they added that the price "relief" offered to buyers by a cut in prices, which on the cash market saw benchmark Illinois prices fall $2 per bushel to some $15.25 a bushel between late August and early October, "may prove to be short-lived".

"Once the harvest finishes and demand accelerates, upward momentum for soybean prices could soon build again," the USDA officials said.

Demand for US soybean exports, which last month hit a record high for a September, "could continue in that manner for several months".

Meanwhile, a firm pace of domestic crushing was confirmed in data from the National Oilseed Processors Association on Monday showing that processors got through 119.73m bushels of the oilseed last month.

While down some 5.0m bushels on the August total, the figure was a little above market expectations, and the 110m bushels a year before.

The comments came as soybean prices on Monday fell below $15 a bushel for the first time since June.

'Unusually cheap'

The follow-up report also highlighted the reasoning behind the USDA's decision to, in the Wasde, raise its estimate for US imports of soyoil, despite highly competitive prices of palm oil, which on Monday renewed its descent in Kuala Lumpur, dropping 2.7% to 2,433 ringgit a tonne for the benchmark December contract.

"Although palm oil is now unusually cheap compared to soybean oil, it cannot contribute to US biodiesel production," because US environmental watchdogs have not cleared the vegetable oil as a suitable feedstock.

Meanwhile, growth in imports of canola oil, which has gained US consent for conversion into biodiesel "will be constrained next year by limited Canadian supplies", depressed by late season crop damage from high winds.

That means a US mandate dictating biodiesel blending of 1.28bn gallons next year, compared with 1bn gallons in 2012, will underpin demand for soyoil – even if the short US soybean crop means sourcing supplies abroad.

The USDA last week near-doubled to a record 350m pounds its forecast for US soyoil imports in 2012-13.