There may be more than holiday weakness behind soft US crop exports revealed on Thursday, with high prices likely to tempt importers to wait for South American supplies to come onstream.

US weekly export sales unveiled on Thursday fell behind analysts' forecasts for crops, with only wheat, at 464,700 tonnes, narrowly beating market estimates.

"Export sales this morning were disappointing with corn and soybean sales not even close to trade estimates," US broker Benson Quinn Commodities said.

Corn sales of 369,100 tonnes fell short of trade estimates of 500,000-700,000 tonnes, while soybeans sales were, at 552,700 tonnes across the current and next marketing year, short of expectations of a figure of at least 700,000 tonnes.

Cotton export sales were negative for 2010-11, by 40,800 running bales.

The data were "poor across the board", US Commodities said.

Patience pays?

However, while some observers attributed the weakness to the influence of the end-of-year holiday season, Tim Hannagan at rival broker PFGBest questioned buyers' appetite to snap up US crops at high prices when South America was close to corn and soybeans harvests .

"And South American farmers have to sell. They don't have the option to store it like we do – they haven't got the storage.

"That makes hanging on for now an interesting proposition for importers," he said, while adding that demand would return in spring from importers, such as China, which had "used the US as a grocery store".

Argentina doubts 

However, the ability for many buyers to wait may be limited by their need for immediate supplies, a factor Macquarie analysts have said may revive US corn exports early in 2011.

Furthermore, hopes for Argentina's corn and soybean harvests have suffered a series of downgrades, thanks to a dearth of rainfall.

Informa Economics on Thursday cut to 23.8m tonnes, from 24.4m tonnes, its forecast for the country's 2010-11 corn crop.

The Buenos Aires Grain Exchange, in its first estimate for the season, pegged production at 20.4m tonnes, down from 23.2m tonnes in 2009-10.

Persistent rains

However, hopes for Brazilian corn and soybeans have remained intact, thanks to regular rains after a dry start to the season, which delayed sowings.

Separately, Brazil's official crop bureau, Conab, kept its soybean production forecast at 68.6m tonnes, with potential for an upgrade if rains continue to prove abundant.

"If the expected area is confirmed and favourable weather conditions seen so far continue, the crop could top the  estimated total volume," Conab said