Fading hopes and growing fears helped soybeans and wheat, the laggards early in the week, play catch up with corn.
"Perhaps launching the baby, bath and the entire kitchen sink out the window yesterday was not such a good idea," grain traders at a major European commodities house said.
The weakening hopes aspect reflected ideas about rain in the US Midwest, as disappointing precipitation overnight revived doubts of the GFS model, which has trended wetter, compared with its European peer.
David Tolleries at WxRisk.com was one sceptic.
"The GFS is wetter and continues to run wetter than any of the models, and continues to show significant areas of heavy showers and thunderstorms in the day one-to-five day time frame," he said.
"I do not believe that the GFS solution is correct."
Cooler, but dry
At Country Futures, Darrell Holaday said: "oHolad
The bottom line is that we are going to see cooler temperatures in most of the Corn Belt and the Plains in the next few days, and we will see cooler temperatures in the next two weeks in the Corn Belt than we have seen in the last two weeks.
"But it should also be noted that there is no significant indication of increased rainfall."
And rain is what consumers and farmers were hoping for to boost yields of, in particular, a soybean crop which is not yet past redemption.
Soybeans for November, the best-traded contract, closed up 3.0% at $16.15 ½ a bushel, nearly wiping out the losses of the last session.
August soybeans added 2.7% to $16.94 ¼ a bushel.
Russian export curbs?
The mounting fears concerned in particular wheat, as talk mounted that Russia is poised to introduce some kind of restriction on grain exports, amid further gloomy talk about its harvest.
"Some talk around the Russian wheat crop not yielding as expected has also helped lift the market today," the European commodities house said.
"With the Russians' recent history of imposing an export embargo last time they suffered a crop problem the market is especially aware of any Russian crop scare."
At FCStone, Mike O'Dea said: "Russia is back in the news this morning, with reports that due to drought/short crop we may see an embargo or export tax.
"This has pushed the wheat futures higher."
Country Futures' Darrell Holaday flagged "some thoughts that we may see some restriction on former Soviet Union wheat exports in the form of a tax".
There were some negatives for wheat too, in terms of the lack of competitiveness of US supplies even in a market whose generally elevated prices prompted Jordan to ditch all offers in a tender for 100,000 tonnes of wheat.
"It interesting to note that this morning French wheat would deliver into the US Gulf at approximately $330 a tonne, and US FOB offers are in the $340-a-tonne area," Mr O'Dea said.
"US wheat is still overpriced. Watch export sales closely tomorrow."
Still, Morocco cancelled out some concerns by issuing a tender for 300,000 tonnes of US wheat, while Libya bought 50,000 tonnes optional origin.
After the close, Iraq was revealed the buyer of 150,000 tonnes of Russian wheat (maybe getting its order in before taxation or embargo strikes).
Chicago wheat closed up 3.0% at $9.03 ¼ a bushel.
And, signally, closer to Russia, Paris wheat did even better, despite tackling a strong euro, which appreciated against the dollar amid hopes that the eurozone will beef up its ammunition for bailing out indebted nations such as Spain.
Paris wheat for November added 3.8% to E260.50 a tonne, with London wheat for November soaring 3.9% to £187.25 a tonne.
Corn from Brazil
This left corn as the laggard, in part because it had fallen less on ideas of rain, being more past hopes of salvation than soybeans.
However, some demand fears were evident too, with much comment on Smithfield's confirmation that it had bought Brazilian corn for August/September shipment to the US east coast, with talk of Brazilian prices of $290 a tonne, plus shipping of $30-40 a tonne, compared with $345 a tonne in US Gulf ports.
"Corn basis continues to slide as the world's largest pork producer said they will import corn from Brazil," Paul Georgy at broker Allendale said.
Further US purchases of Brazilian corn would be a "strong indication that end users are looking elsewhere for grain and may be a real indicator of rationing", US Commodities said.
Low water setback
And as an extra downer to US competitiveness, the weak rainfall that is destroying crops is adding to transport costs too by lowering river levels (as happened in the Rhine and Danube in Europe late last year).
"Mississippi river levels have been affecting the front month cash prices. Water levels have been so low this summer that the barges have to be loaded with less grain," US Commodities said.
"The effect on prices is bearish," with less efficient use of barges increasing shipping costs, "which widens the basis levels at origin".
Furthermore, ethanol production again fell, down 6,000 barrels per day last week to an average of 796,000 barrels per day, a fresh low since records began two years ago and fuelling ideas that the US may relax its ethanol mandate to ease pressure on the industry and corn supplies.
Corn for December added 1.3% to $7.88 a bushel.
Among soft commodities, New York raw sugar managed to make it to a positive close, up 0.3% at 23.57 cents a pound for the October contract, despite industry data showing a sharp revival in the cane harvest in Brazil's important Centre South producing region in the first half of July.
The recovery was offset by weak sugar content in the cane, meaning actual product for turning into sweeteners or ethanol was marginally lower than a year before.
A drop in the dollar, of 0.5% on a trade-weighted basis, helped too, in making dollar-denominated assets more affordable to buyers in other currencies.
Indeed, New York coffee perked up to close 0.5% higher at 176.30 cents a pound.
And cocoa for September added 1.0% to $2,230 a tonne, getting some boost too from background concerns at potential impact from the death of John Atta Mills, the president of Ghana, the second-ranked cocoa producing nation.