The rally in US crops ran out of steam as the flow of fund money responsible for driving it higher even against a rising dollar faltered in later trade.
Crops started in live trading where they left off the night before, with Chicago wheat jumping to $5.83 ½ a bushel, its highest level for five months, and soybeans hitting a two-month high of £$10.49 a bushel.
"Prices are higher across the floor again, driven by ongoing speculative buying," Vic Lespinasse, marketwatcher at GrainAnalyst.com, said in early trading minutes.
However, the rally petered out as "large scale speculative buying dried up after the first hour or so of trading", he added later. Profit-taking had a big hand too.
January soybeans closed down 2.5 cents at $10.27 a bushel.
Corn had worse luck, ending 4 cents lower at $3.98 a bushel for December delivery.
Wheat, which has been the focus of so much of the recent action - the crop unusually on both Monday and Tuesday captured higher trading volumes than soybeans, when electronic and pit trading were combined - ended down 8.5 cents at $5.66 ¼ a bushel for December.
And all this despite a weaker dollar, which eased within a hair's breadth of $1.50 against the euro.
If all that boded ill for European crops, with a lower Chicago market and stronger currencies to deal with too, there was further soft news waiting in the wings.
Customs data showed UK wheat exports at 438,000 tonnes in the July-to-September period, compared with 723,000 a year before.
"With wheat exports only 45,000 tonnes greater than imports to the end of September, that's no great shakes," David Sheppard, the managing director of grain merchant Gleadell, told Agrimoney.com.
London prices faced a struggle with exports running at "pretty low levels".
Nonetheless, they managed to end, in the main higher with the January contract adding £0.40 a tonne to £108.00 a tonne. The July 2010 contract added £1.00 o £115.00 a tonne.
However, given the market's close before Chicago losses really set in, London grains may find it tricky to hold on to their gains on Thursday.
Paris milling wheat ended lower, down E0.50 to E134.25 a tonne for January.
Many softs had better luck, and were able to enjoy the dollar's weakness.
March raw sugar ended 0.20 cents higher at 23.30 cents a pound, with rising prices in India, the world's biggest consumer, also helping out.
March cocoa soared nearly 4% to $3,258 a tonne, with some investors saying the commodity had fallen too far, both on fundamental and technical grounds, from last month's 30-year highs.
London contracts were pulled up too, with white sugar for March ending up $13.20 at $624.50 a tonne and cocoa jumping £62 to £2,120 a tonne for the same month.