Corn and soybean futures rallied on the Chicago Board of Trade as weather forecasts indicated drier conditions for grains planted in the US Midwest.
New York-traded cocoa climbed its most in 10 months on news that Ivory Coast has forward sold a large portion of its new crop ahead of schedule, prompting worry about less-than-expected selling from the No. 1 cocoa producer later in the year.
The 19-commodity Thomson Reuters-Jefferies CRB index settled up 0.6 percent for its second gain in as many days.
Brent crude out of Europe's North Sea closed up 31 cents at $109.40 a barrel, its highest settlement since April 2.
The rally in Brent came as US gasoline surged due to refinery problems during the peak summer driving season and rising prices for ethanol credits.
In contrast to Brent and gasoline, US crude oil finished down 32 cents at $106 a barrel.
Gold prices rose as the dollar fell after US data showed consumer prices picked up in June and underlying inflation pressures showed signs of stabilizing. This fed the belief that the Federal Reserve will start reducing its bond purchases later this year, not imminently.
The spot price of bullion hovered near $1,292 an ounce by 5:30 p.m. EDT (2130 GMT), up 0.8 percent from Monday.
Traders said investors in bullion are expected to closely watch Fed Chairman Ben Bernanke's semi-annual testimony to the US Congress committees on Wednesday and Thursday for further clues on when the central bank would began tapering its $85 billion in monthly mortgage-backed securities purchases.
In copper, the three-month futures contract on the London Metal Exchange ended up 1.13 percent at $6,998 a tonne, after falling half a percent in the previous session.