The firm start to Monday for agricultural commodities gave way to something altogether more patchy, as Chinese inflation data, and in particular Friday's disappointing US jobs statistics, weighed on markets.
"Those numbers pressured equities and energies, and that has been hard for the grains to shake off," Darrell Holaday at Country Futures said.
With a risk-off feel in evidence, speculators felt more confident about selling
New York arabica coffee for May closed down 2.7% at 178.05 cents a pound.
The prospect on Tuesday of the Brazilian farm ministry's first estimates for the 2012-13 cane crop added an air of caution to trading.
Chicago had something of a similar feel too, with the US Department of Agriculture on Tuesday set to reveal its latest much-watched Wasde world crop report.
This will be scoured in particular for further downgrades to the drought-struck South American
However, more complex than in sugar, nerves ahead of the report were reflected in a range of positioning between crops – and notably in the unwinding of short wheat, long corn or soybean spreads.
"Spread trading is dominating the grain markets ahead of USDA's Wasde projections," Darrell Holaday at Country Futures said.
"The spread trading dominating is the unwinding of the corn/wheat spreads and the soybean/wheat spreads. That has supported wheat versus the corn and soybean markets today."
As a further twist, USDA weekly crop progress data due later on Monday are expected to show US corn sowings hitting 7-9% completed.
US Commodities said: "This is a record pace and should lead to above-trend yields.
"The trade should soon discuss yields of 166-167 bushels an acre," compared with the 164 bushels an acre the USDA is currently talking about."
Meanwhile, as ideas for corn production rose, those for wheat received a – potentially temporary – booster from the prospect for cold weather, which given that US winter wheat is unusually forward this year, poses a particular threat.
"Concern about colder temperatures has supported wheat markets to some extent," Mr Holaday said.
Benson Quinn Commodities said: "There could be some damage to hard red winter wheat in the northern Plains," if adding that this "shouldn't be enough to tip the supply scales".
Wheat for May rose 0.7% to $6.43 a bushel in Chicago.
Chicago May corn fell 1.4% to $6.49 a bushel, while May soybeans dropped 0.2% to $14.31 a bushel.
Still, for more convincing gains, New York
Anand Sharma, trade and textile minister in India, the second-ranked exporter, said that no further shipments would be permitted "until further orders", and raised doubts over 2.5m bales already registered for departure but not transported.
"The quantities that were registered earlier are still being scrutinised and revalidated," Mr Sharma said.