Tuesday may not be counting exactly as a "turnaround" one, those phenomena of Chicago lore which reverse a strong price trend of the previous session.

But it certainly rated as a turgid one in early deals, as investors balanced a number of stimuli, and ended up unsure of which way to tread.

There were some negative stimuli around, such as the continued worries over whether elevated prices are already doing enough to hamper demand.

For corn especially, a succession of weak US export sales data, soft US ethanol production statistics (and Poet's announcement of plant shutterings), and a weaker-than-expected cattle population on feedlots have sparked ideas of demand rationing happening at a clip.

'Slow exports'

But there are some concerns over wheat too, at least of the hard red winter variety, which Benson Quinn Commodities described exports as "slow, offering some supply cushion into the next marketing year".

"Global wheat buyers continue to tender, but the bulk of the supply continues to be sourced from other origination points," the broker said.

Improving conditions in the Ukraine, where talk is of a 20-30% rebound in yields this year, a failure to confirm talk of Russian imports, and ideas of strong Canadian spring wheat sowings also represent a little bit of a negative.

Meanwhile, there is some caution in markets broadly ahead of a string of data from the world's top two economies on Friday, including indicators on China's manufacturing sector and a key US jobs report.

The US Federal Reserve starts a two-day policy meeting today too.

GFS vs EU

However, it was difficult for investors to get too bearish too, without an improvement in the South American weather forecast, whose deteriorated aspect has prevented the early harvest in Brazil offering much in the way of pressure to prices, as might have been expected.

"South American weather is becoming of more importance as GFS and EU weather models have come to more agreement on a drier outlook for Argentina and southern Brazil into February 10," Benson Quinn said.

 "The forecasts currently more of a concern for the Argentine corn crop than for soybeans," given the crops' development cycles.

"But with GFS models going drier some analysts have started to trim Argentine soybean production estimates."

The GFS model has previously offered a wetter, more comforting pattern for farmers than the European one.

'Moisture desperately needed'

At Phillip Futures, analyst Joyce Liu said: "Weather in Argentina and Brazil has to improve to meet their target forecasted output to replenish tightening global stocks.

"Moisture is desperately needed in corn and soy fields in the next few days."

And actually a bit of dryness too in central and northern Brazil, where crops are more advanced, and wet weather is hampering early harvest, and the supply of soybeans to ports and hungry import markets.

"All eyes are also watching out for potential infrastructure bottlenecks in Brazil, which had accepted bumper orders for its supposedly bumper crop," Ms Liu said.

Boat line-ups in Brazil's ports are reportedly reaching the equivalent of 45 days.

Kansas decline

Meanwhile, one other major weather concern, the drought in the US Plains, revisited markets after Kansas, the top wheat-growing state, revealed a further deterioration in its crop this month, blaming "limited moisture".

The proportion rated "good" or "excellent" fell four points over January to 20%, compared with 49% a year before.

The proportion rated "poor" or "very poor" rose eight points to 39% - up from 12% at the end of January 2012.

And technically, markets offered a better aspect too, with Mike Mawdsley at Market noting how corn in the last session "fought back and slowed over the downtrend" and soybeans clung on to end above their 20-day moving average.

"It was a good day for grains and soybeans, to start the new week," he said.

Small moves

Chicago corn for March added 0.1% to $7.30 ½ a bushel as of 09:40 UK time (03:40 Chicago time) to set course for another showdown with its 75-day moving average, at a little under $7.31 a bushel.

The contract has oft challenged its 75-day line this month, and sometimes managed to temporarily break above it, but has not actually managed to close above it since November.

The 50-day moving average, at a little under $7.24 a bushel, has been comfortably secured for now.

Wheat for March stood up 0.25 cents at $7.79 ½ a bushel, pretty much at the same level as its 10-day moving line, leaving soybeans the weakest of Chicago's big three.

The March soybean contract stood 0.1% lower at $14.46 a bushel.

Nonetheless, Phillip Futures' Ms Liu, flagging China's "positive soybean crush margins and rising demand for soybean meal", and record pace of processing, forecast "continued strength in front-month soybeans up to $14.50-a-bushel levels by first week of February".

'Some irreversible damage expected'

In New York, raw sugar echoed grains in reporting a small gain, up 0.1% at 18.74 cents a pound for March, continuing a recovery fuelled by concerns that a huge speculative net short position may mean that selling pressure from that category has already run its course for now.

Heavy rains in Australia are, while causing widespread flooding, seen as bringing some benefits as well as disaster.

"Some irreversible damage is expected, particularly around Bundaberg which is experiencing its worst flooding on record," Luke Mathews at Commonwealth Bank of Australia said.

"However, some regions will benefit from the increased moisture."

Cotton headway

But New York cotton maintained a firm place in investors' good books, adding 1.6% to 82.35 cents a pound for March, helped most lately by a downgrade by Cotlook to its hopes for the world cotton supply surplus, citing increased demand.

In Australia, for cotton too rain is proving a mixed blessing.

"Most New South Wales cotton crops are expected to benefit from the additional moisture", Mr Mathews said,

But in Queensland, "the worst inland flooding is throughout the Darling Downs region where production losses are likely".