It’s not just potash. Across the board, commodities prices are soaring. Last week, light, sweet crude closed at more than $130 a barrel, more than double the price 12 months ago.

Commodities are the first growth industry of the 21st century. The prices of energy, basic metals and foodstuffs have soared, and so, some say, has speculation. This year alone, cocoa is up 40 percent, copper has soared 24 percent, and corn has risen 33 percent. And the price charts for some commodities are beginning to look suspiciously like the Nasdaq fever line in 1999, just before the tech-laden stock index crashed in March 2000. And, as the economy continues to work through the more recent crash in home prices, the question inevitably arises: Is there a commodities bubble brewing?

Possibly, say many experts.

Quick Profits

“Certainly, we’re seeing a lot more interest (in commodities) across the board,” says Barry Cronin, chief investment officer at Taylor Investment Advisors, a Greenwich money management firm. “There’s no mistaking that there’s a significant amount of speculative money in the market.” But is it a bubble? “That’s the $100,000 question,” Cronin says.

Price bubbles involve irrational behavior by investors drawn to the prospect of quick profits. But such manias aren’t entirely measurable. Instead, you have to look at several different ways to measure bubble behavior. And by those measures, the bubble in commodities is still forming, but it’s not at full froth.

Nevertheless, new signs of commodities mania keep bubbling up. The basic sign is a near-vertical rise in prices, says Ben Inker, director of asset allocation for the GMO funds. “If you look at the way oil has been moving lately, it’s almost inconceivable that there is information about the future supply and demand of oil that’s driving this,” Inker says. “It cannot be the case that, relative to three weeks ago, we have information that would make the price of oil go up that significantly.” The price of a barrel of light, sweet crude oil has soared 17.4 percent the past three weeks.

And Wall Street, for one, thinks that the market for commodities is hotter than the market for stocks.

Responding to price run-ups, the mutual fund industry in the past 12 months has rolled out dozens of commodity-related exchange traded funds, with tickers like MOO — a fund that specializes in agricultural stocks. Others include a coal fund (KOL) and a raw materials fund (RAW). The funds typically invest in commodities futures contracts and have attracted billions in new investments in the past 12 months.

Pension Funds

Pension funds and other big, institutional investment pools are starting to pour money into commodities, too. Calpers, the California public pension fund, announced in March that it’s devoting $1 billion to commodity investments, up from $450 million in past years.

Individual investors, too, are choosing commodity index funds. PowerShares DB Agriculture ETF has seen $22.5 billion in new money flow through its doors the past 12 months. Until commodity ETFs came along, average investors were largely excluded from the commodities markets. “It’s not just for the ultrahigh-net-worth investor anymore,” says Robert Maroney, principal at Connecticut Investments, an investment advisory service.

In fact, the mutual fund industry has rolled out 52 new exchange traded funds that invest in diversified commodities, energy or precious metals in the past 12 months, according to industry tracker Morningstar.

That’s rarely a good sign: Fund companies are notorious for rolling out many sector funds at the top of a bubble.

Every bubble starts with a rational investment thesis and, in this case, it’s the roaring economies of India and China, whose voracious appetites for steel, copper and oil have been pushing up the prices of raw materials. Improved diet and nutrition in emerging markets, as well as U.S. mandates for biofuel use, have driven up the cost of food.

Inflation Rising

India and China also seem to be in the throes of a wage-price inflation cycle. China’s inflation rate rose to 8.5 percent the past 12 months ended April, versus 3.9 percent in the USA for the same period. India’s inflation rate rose to a 3-year high of 7.6 percent. Wages in both countries have skyrocketed. As a result, the prices of Chinese imports — long an important method of controlling price inflation here — have started to rise sharply.

Normally, whipping inflation is a job for a nation’s central bankers. They push up interest rates to slow down the economy and cool off demand, shutting down inflation. But most central banks are doing the exact opposite.

The question, then, is whether the rush of money into the commodities markets have helped push prices higher than they would be otherwise.