Gold prices fell sharply, snapping a monthlong streak higher, while oil prices receded. Agriculture futures plummeted as wheat and corn prices fell the daily limit permitted by the Chicago Board of Trade.

Two inflationary trends of the past six weeks -- oil's rise and the decline of the U.S. dollar -- reversed course Tuesday, kicking away major supports for precious metals. Investors will often turn to gold and silver to hedge against fears of inflation. As oil prices slipped below $80 a barrel and the dollar gained back some ground against the euro, precious metals prices tumbled.

December gold fell $17.80 to settle at $736.30 an ounce on the New York Mercantile Exchange, its biggest drop in more than a month. December silver lost 40.5 cents to close at $13.45 ounce.

Scott Meyers, senior trading analyst with MF Global's Pioneer Futures, attributed the drop to "a major round of profit-taking" following gold's climb of nearly $100 an ounce since mid-August.

"It's something that wasn't that unexpected," he said. "At some point it was going to do this."

The U.S. dollar on Tuesday appeared to have stemmed its slide versus the euro -- at least for the time being -- after descending to an all-time low a day earlier. The greenback has carved fresh lows against the euro seven of the past eight trading days, as the fallout from the Federal Reserve's interest rate cuts and weak economic data took its toll on the U.S. currency.

The 13-nation euro bought $1.4152 in afternoon trading, off its peak of $1.482 on Monday.

With the dollar trading higher and little other news to go on, energy prices retreated. Because commodities priced in dollars become more attractive to foreign buyers as the dollar falls, the U.S. currency's advance on Tuesday effectively acted as a price markup, damping demand.

Light, sweet crude for November delivery shed 20 cents to $80.04 a barrel on the Nymex, after sliding as low as $78.87 in earlier trading. November gasoline futures were roughly flat at $1.982 a gallon.

Looking ahead to weekly data on energy inventories, analysts expect the Energy Information Administration to report increases in stockpiles of gasoline and distillates. Analysts polled by Dow Jones Newswires expect gasoline inventories to rise by 400,000 barrels and distillates, which include diesel fuel and heating oil, to rise by 700,000 barrels. Crude oil supplies are expected to fall by 400,000 barrels.

Elsewhere, industrial metals traded in a mixed range on the London Metal Exchange. Most advanced, with lead, nickel and tin leading the gains, while zinc prices dipped. Copper prices rose in London and New York. The Nymex December copper contract rose 1.95 cents to end at $3.711 a pound.

In Chicago, agriculture futures plunged as investors questioned whether the dollar's rise would hurt foreign demand for U.S. agriculture products. Strong export sales have bolstered prices for weeks, sending wheat and soybeans to multiyear highs.

"These markets are very much reliant on exports, which are in turn reliant on a weak dollar," said DTN analyst Gary Wilhelmi.

With wheat prices at record levels and world supplies dwindling fast, farmers have begun winter wheat plantings in earnest in the U.S. The Agriculture Department reported late Monday that 49 percent of the U.S. crop has been planted, on pace with the historical average. At the same time, the country's corn harvest is currently under way and expectations are for a robust crop.

December corn declined 20 cents, the maximum price swing allowed, to close at $3.4875 a bushel on the CBOT. December wheat dropped the maximum 30 cents permitted to $9.225 a bushel. Soybeans for November delivery tumbled 47.75 cents to settle at $9.4375 a bushel, near its daily limit of 50 cents.