The best that can be said for Chicago crops is that they displayed credentials as assets uncorrelated to other major investments.

Most markets were buoyed by data showing 36,000 US jobs were lost in February, less than the 50,000-65,000 analysts had expected. Shares, for instance, gained 1% on both sides of the Atlantic.

And commodities had the extra potential impetus of comments from Chinese premier Wen Jiabao signalling a continuation of the loose fiscal and monetary policy in a country which is a huge buyer of raw materials.

Oil, indeed, took the bait, topping $82 a barrel at one point to set a fresh seven-week high.

The dollar,meanwhile, was stable.

League of their own

But crops trod a furrow of their own, ending their seesaw pattern, which should have made Friday an up day, which it certainly wasn't for the grains.

Wheat closed down 1.7% at $4.82 ¼ a bushel for March, the worst for a spot contract for nearly a month. The May lot ended 1.7% lower at $4.93 ½ a bushel.

Corn lost even more, slipping 2.0% for both March delivery, which finished at $3.64 ¾ a bushel, and May, which closed at $3.75 ½ a bushel.

Revision jitters 

Triggers for a bearish stance were not difficult to find with, for instance, the Rosario Grain Exchange raising its estimate for Argentina's crop, albeit not above levels already tested by analysts, and reports that America's 2009-10 harvest may come in bigger than had been thought.

The US Department of Agriculture will on March 10 issue a fresh estimate for the crop, adjusted for late harvesting, with many traders having expected downward revision.

This, however, is now not looking so certain.

A Minnesota producer yesterday reported a 170 bushel-an-acre corn yield on the winter harvest," US Commodities said, adding that the figure "added validity" to talk of 50m-100m bushels being added to the US harvest figure.

Disease fears 

And then there is the prospect of farmer selling, which many observers expect to accelerate as farmers sell to avoid the risk of disease showing up in crops harvested, after all, in dismal autumn conditions.

"Financially, producers are in condition to remain strong holders of supplies," Mr Holaday said.

"But there is also concern about the quality of corn in the bins - high moisture - and that could prompt some producer selling before the weather warms up."

While wheat had less fundamentally going against it, there remains a backdrop of huge global supplies.

Mr Holaday said: "Wheat continues to be wheat. The fundamentals are negative and rallies are seen as selling opportunities and the buying simply dries up."

Soybeans at least managed to scrape to a positive close, adding 2.25 cents to $9.34 ¾ a bushel for March and 0.75 cents to $9.42 ¾ a bushel for May.

The reason for their relative resilient was not immediately clear, although economic hopes for China, the world's biggest buyer, can't have hurt.