It was a positive day for commodities anyway, amid revived hopes for Chinese growth, after a firm set of July data last week on the health of the world's second-largest economy, and a huge consumer of raw materials.
The CRB commodities index added 1.0%.
But agricultural commodities did especially well - despite news that hedge funds have, for the first time, gone net short in the asset class for the first time on record.
Many soft commodities hit multi-month highs, although the headlines were grabbed by corn and soybeans, which had the unexpected boost of downgrades by the US Department of Agriculture, in its much-watched monthly Wasde crop report, to estimates for domestic stocks of both crops at the close of 2013-14.
The USDA cut its forecast for the corn yield, reflecting dryness in the western Corn Belt, and its estimates for soybean yield and area too, following a resurvey of plantings in 14 states.
That is not to say that the US, the world's top grower of both crops, looks on for anything but strong harvests, especially of corn.
Indeed, the latest run of the GFS weather model, while not obliging by altering ideas of a dry Midwst pattern this week, at least made the outlook for the six-to-10 day horizon "considerably wetter over the central Plains into the lower western Corn Belt", WxRisk.com said.
"With a return to more seasonal mid-August pattern, the model develops an increase in showers and thunderstorms over the central Plains and lower portions of the western Corn Belt," the weather service said.
"I would not call this a 'wet pattern', but it certainly is wetter than what the data was showing earlier."
But soybeans were already looking strong, even before the Wasde report, after China purchased a further 713,000 tonnes of new crop supplies from the US, taking its total in the last week just released through the USDA daily alerts system, ie large orders only, above 1.0m tonnes.
(The USDA also on Monday unveiled the sale of a further 140,000 tonnes of soybeans to an "unknown" destination.)
And with the USDA lowering by 1.9 bushels per acre, to 42.6 bushels per acre, its forecast for the domestic harvest, and cutting by 75m bushels to 220m bushels its forecast for US stocks at the close of 2013-14, futures were unlikely to end anything but strong.
Especially with soymeal jumping 4.2% to $371.00 a short ton for December delivery, after the USDA cut its forecast for domestic production of the feed ingredient, flagging the role of high prices in cutting demand.
November soybeans closed up 3.6% at $12.25 ¼ a bushel.
Against the grain
That was better than new crop December corn could manage, in closing up 2.4% at $4.64 a bushel.
(Indeed, the new crop soybean: corn ratio closed at a whacking 2.64: 1.)
Still, that was quite some victory given that the contract earlier set a fresh lowest-since-late-2010, of$4.46 ½ a bushel, and that there are considerable doubts over the USDA's downgrade in the US corn yield, to 154.4 bushels per acre, which was behind the price recovery.
Many analysts have been raising estimates to levels above 160 bushels per acre, the latest being Deutsche Bank, after attending the MDA crop tour, as the investment bank cut its forecast for US corn futures to $4.20 a bushel as an average for the last three months of this year.
Hedge funds take profits
"The trade will be more willing to embrace a conservative US soy yield forecast than a cut in the 2013 US corn yield," said Richard Feltes at broker RJ O'Brien, which came in with an especially gloomy corn forecast last week.
"The correlation between cool Augusts and above trend corn yield is strong.
"Talk of $4.25-a-bushel December corn futures will abate short term," he said, if adding that "corn lows in our view still not in".
Nonetheless, with the USDA also unveiling 252,153 tonnes of corn exports to Mexico, for now, many investors were tempted to book profits on their record net short in the grain.
'Relatively tight stock situation'
For wheat, the reaction to the Wasde was more mixed, despite it cutting the forecast for US stocks at the close of 2013-14 by 25m bushels to 551m bushels.
"This is relatively tight wheat stock situation," Darrell Holaday at Country Futures said.
"The problem is that world production was increased 7m tonnes. World stocks are plentiful and corn supplies are increasing."
Sure, the USDA mopped up most of the extra output with extra consumption.
But, with output centred on major exporting regions of the European Union and low-cost Kazakhstan and Ukraine, the revisions were not taken as bullish.
Chicago wheat for September gained, but by a modest 0.2% to $6.35 a bushel. The December lot edged 0.2% higher to $6.49 a bushel, meaning its premium has fallen back to $1.85 a bushel, comfortably below figures above $2 a bushel earlier in the month.
Paris wheat for November gained, but by the minimum E0.25 a tonne to E183.25 a tonne, and only after hitting a contract low of E182.00 a tonne earlier.
'Smallest crop since 2009'
Soft commodities enjoyed a firm day, generally, too especially cotton, which for December delivery returned above 90 cents a pound for the first time in 16 months, thanks to Wasde crop revisions.
The report trimmed the USDA estimate for US stocks at the close of 2013-14 by 100,000 bales to 2.8m bales, reflecting a small downgrade to the figure for domestic harvested area, and a cut of 18 pounds per acre, to 813 pounds per acre, in the yield forecast.
"Production is reduced 447,000 bales to 13.1m, the smallest since 2009," the USDA said, also trimming its forecast for world cotton inventories, rather than increasing it as investors had expected, reflecting too a 1.0m-bale downgrade to the Chinese harvest.
December cotton closed up 1.3% at 90.08 cents a pound in New York.
Cocoa for December set the contract's highest close in eight months in New York, adding 0.8% to $2,499 a tonne, amid continued concern over dryness in West Africa, and ideas that top producer Ivory Coast has sold more beans forward than had been thought, meaning less unfulfilled selling pressure.
And raw sugar for October added 1.1% to 17.16 cents a pound, the first close by a spot contract above 17.00 cents in nigh on three months, amid a reassessment of Unica Brazilian production numbers released last week.
"On the face of it, these were bearish numbers, but expectations apparently were of a higher ATR [sugar concentration in cane]," Nick Penney, senior trader at Sucden Financial, said.
"What may have caught the eye were the comments regarding recent frost damage accompanying the numbers," as highlighted by Agrimoney.com at the time.
"Preliminary investigations show that there has been damage to the core and leaves of the cane and that ATR is expected to have been reduced in the affected plants."