Soybeans broke back above $12 a bushel for the first time in a month, as talk of further Chinese buying helped traders overcome nerves ahead of a key US report.
Technical factors had some part to play in the surge of 4.8% to $12.26 a bushel in Chicago's August bean contract at one point.
The contract, which stops Chicago trading on Friday, has reached an endgame which typically provokes price swings as investors exit positions, typically amid small volumes of trade which make prices easier to swing.
Indeed, volumes for August contract were below 2,600 lots, in late deals, when that for November beans was more than 76,000 lots.
But the trend was echoed in forward contracts, with new crop November beans up nearly 3% at $10.39 ½ a bushel at their day high, reflecting hopes for Chinese demand.
While China's Ministry of Commerce was reported on Monday to have forecast a halving in the country's soybean imports this month, compared with July, this projection was disputed by another Chinese officials.
"The deputy chief of the economic and trade department under the National Development and Reform Commission said China's domestic bean output growth can't match the rate of rising demand so bean imports will continue to rise," Vic Lespinasse, the GrainAnalyst.com marketwatcher said, failing to name the official personally.
"He also said the government will encourage processing plants to increase their bean reserves and that China's bean imports will total 40m tonnes this year versus 37.4m tonnes last year.
"If he is right, this is friendly for US bean export prospects to China."
Furthermore, the US Department of Agriculture announced that China bought 110,000 tonnes of US beans for the next crop year, which begins next month.
August beans stood 3.1% higher at $12.07 a bushel in late trade, with the November contract up 2.8% at 10.38 ¼ a bushel.
The rises failed to have a huge spillover effect on other crops, whose investors remained fixed on the prospect of the USDA's latest crop report due out on Wednesday.
Chicago corn for September maintained gentle upward progress, adding 2.75 cents to $3.27 a bushel, with the December contract 1 cent higher at $3.31 ½ a bushel.
Wheat, however, lost early gains. The $5 a bushel mark proved the barrier some traders had reported, with September contract getting to $4.99 ¾ a bushel only to rebound lower.
The contract stood at $4.87 a bushel in late deals, down 7.25 cents on the day and within 1% of the 2009 low for a near-term Chicago lot.
European wheats were lower too, with London's November contract ending down £0.65 at £97.60 a tonne and Paris contracts generally a touch lower, with the notable exception of November, which added E0.25 to E130.75 a tonne.
Wheat has remained under pressure from a string of estimates of strong European yields, the latest from the Czech Republic and France.
Rapeseed did better, however, taking a cue from soybeans and ending up E4.50 at E276.75 a tonne in France.