Crops still weren't luring buyers on Thursday, even at cut prices.
The bank cited dry weather in much of the area, especially troublesome given the advanced average age of cane stands.
Macquarie cut its forecast for the region's cane output by 20m tonnes to 500m tonnes, getting its revision in before cane industry group Unica has even made its first, and long-awaited, estimate.
But gains elsewhere were hard to find, in risk assets in general, which limped towards the end of a strong quarter, continuing to be sapped by Wednesday's poor US durable goods orders data for February, and with some concerns about eurozone sovereign debt re-emerging too.
A strike in Spain in protest at austerity measures saw to that.
And the safe haven of the
The average commodity, as measured by the CRB index, fell 1.8%.
And many agricultural commodities managed to outpace even that decline, notably in Chicago, which extended the week-long trend of overnight rises which have given way, especially in grains, to collapses in the live trading session.
Indeed, anyone who has not already locked in prices may certainly be looking at planting
That took the soybean: corn ratio to a year high of 2.49, up from levels below 2.0 late in 2011.
But wheat was worst performer of Chicago's big three, shedding 2.9% to $6.12 ½ a bushel for the benchmark May contract, a two month lot for a spot lot.
May corn also closed at a two-month low, of $6.04 a bushel, down 2.6% on the day.
As ever of late, soybeans were the best performer, among a bad bunch, shedding 1.2% to $13.55 ½ a bushel for May.
Corn's performance in particular appeared to be down to the continued realisation of the danger presented by two US Department of Agriculture reports on Friday.
"Investors are looking to reduce risk exposure and are preparing for negative corn data," US Commodities said.
One report, on US spring sowings, is expected to show a huge corn area estimate, only encouraged by recent balmy weather.
But there is increasing focus too on the second briefing, on grain inventories, the latest in a series of quarterly reports which have gained notoriety even in Europe.
"Corn futures have fallen by the daily limit on the day of the past three quarterly stocks reports," UK grain trader Gleadell said.
And investors have reason to fear or another bearish report this time, given the warm winter which meant livestock farmers may have used less feed than had been thought.
"I see old crop stocks numbers and usage numbers as more important than new crop acreage," GrainAnalyst.com trader Matthew Pierce said.
"Following one of the warmest winters on record, feeders realise their early estimates are way too high.
"If the USDA drops soymeal, corn and wheat feedings, traders could see an increase across the board in old crop stocks."
As an extra incentive to sell corn, weekly USexport sales data for the grain were dire, at 157,000 tonnes, old crop and new, below estimates of 650,000-800,000 tonnes and the lowest figure since 2004.
OK, the USDA also unveiled corn sales of 120,000 tonnes to China, and a further 120,000 tonnes to "unknown destinations", presumed to be China too, confirming reports of deals.
But corn has a history of rising on the rumour, and selling on the fact, of these deals anyway.
There were plenty of ideas that corn had sold off too far, nonetheless.
"There are legitimate thoughts that the break in corn prices has built in a lot of bearish ideas regarding the stocks number and acreage number that has been surfacing in the last two weeks," Darrell Holaday at Country Futures said.
"It will take a corn stocks number at 6.5bn bushels and acreage number of 95m to prompt a bearish response. And that may be short lived."
But that is an issue for Friday.
Wheat also faced pressure from poor weekly US export sales, of 403,100 tonnes, below estimates of 500,000-750,000 tonnes.
It is also balancing off improved ideas over the US crop against drought threatening Europe's.
"Ideas surrounding the US hard red winter wheat crop just continue to get better with condition reports improving continuously," Mr Holaday said.
European contracts continued to take a little more notice of local conditions, seeing Paris wheat for May close down a more modest 1.9% at E207.25 a tonne, and London wheat for May shed 1.0% to £171.00 a tonne.
"European Union wheat prices are well out against US/South American origins but, with French and UK balance sheets looking finely balanced, this currently is of little concern," Gleadell said.
The non-competitiveness of European wheat was highlighted on Wednesday by an Egyptian tender which showed French grain offered at $300 a tonne, more than $40 above the cheapest Argentine lot.
Soybeans enjoyed better export sales, of 592,000 tonnes, within the range of market estimates, besides a reasonably downbeat report on Paraguay's prospects from USDA attaches in South America.
In Argentina, the Buenos Aires Grain Exchange cut its estimate for the domestic soybean crop by 1.2m tonnes to 45m tonnes, citing losses in the north of the country.
"Despite consistent rain forecasts in Chaco, the showers necessary to interrupt the drought never arrived," the exchange said.
And as an extra help, USDA daily export data showed China buying 120,000 tonnes of US soybeans too.
Back in New York, the selling gave comfort to investors who have built up short positions in many soft commodities, and indeed encouraged more selling.
"Most funds remain bearish due to 2012 being the year of the Brazilian 'on' cycle," harvest," Kona Haque at Macqaurie said, (if adding that "most trade houses we talk to are more bullish").
"The sharp drop in prices over the past month has led to panic selling from origin."