Rice prices retreated further Wednesday, hitting a two-month low on expectations that easing export bans in Asia and a robust crop in Vietnam will boost supplies of the staple food consumed by half the world’s population.

Other commodities traded mixed, with crude oil rising back above $130 a barrel and gold, silver and copper futures falling.

The latest fall in rice prices comes as the government of Cambodia this week lifted a rice export ban imposed in March to stabilize rising domestic prices. Pakistan lifted its own export ban earlier this month, and Vietnam is expected to ease its export ban in July.

Vietnam, the world’s No. 2 rice exporter after Thailand, is also forecast to produce a large rice crop this year, which will likely put downward pressure on prices, said Jack Scoville, rice analyst with Price Futures Group in Chicago.

“Prices have corrected quite a bit in the last week, so buyers are taking a wait-and-see approach,” Scoville said. “Vietnam’s crop is being harvested now and so far it seems to be above last year’s by about 6 percent. It’s going to hit the market pretty soon.”

Rough rice futures for July delivery fell $1.06 to $18.54 per 100 pounds on the Chicago Board of Trade, after earlier falling to $18.45, the lowest since March 20. The contract is down sharply from an all-time high of $25.07 on April 24.

Scoville said the steep decline may signal the start of a correction for rice prices, which have surged 80 percent in the last year amid fears of a global shortage. High prices have sparked food riots in poor countries around the globe and prompted some vendors earlier this year to limit sales to discourage hoarding.

Rice has “run up a lot in the last couple of years, so to have some type of correction is expected sooner or later, and it seems like we’re getting into that area,” Scoville said.

Other agriculture futures traded mostly higher Wednesday. Wheat futures for July delivery rose 2.25 cents to $7.6125 a bushel on the CBOT, and July soybeans jumped 27.25 cents to $13.75 a bushel. July corn, meanwhile, fell 4 cents to $5.94 a bushel.

In energy markets, oil futures rebounded as threats against Nigerian oil facilities fed concerns about global supplies. A Nigerian rebel group, The Movement for the Emancipation of the Niger Delta, threatened attacks on oil installations beginning Thursday to mark the one-year anniversary of President Umaru Yar’Adua’s inauguration.

Light, sweet crude for July delivery rose $1.45 to $130.60 a barrel in early afternoon trading on the New York Mercantile Exchange, after fluctuating between gains and losses for most of the morning. Crude fell $3.34 on Tuesday. The contract passed $135 for the first time last Thursday.

Other energy futures also rose Wednesday. June gasoline futures added 4.2 cents to $3.425 a gallon on the Nymex, while June heating oil futures rose 4.18 cents to $3.841 a gallon.

In precious metals, gold futures dipped Wednesday as the dollar gained against the euro, prompting investors to sell the metal as a hedge against inflation.

Gold for June delivery fell $7.40 to settle at $900.50 an ounce on the Nymex, after earlier falling as low as $888.30.

Other precious metals also fell. July silver fell 5 cents to settle at $17.415 an ounce on the Nymex, while July copper lost 2.1 cents to settle at $3.695 a pound.