A crippling drought decimated crop yields across the country this summer, but overall, farmland prices continue to rise, sparking fears a bubble may be brewing.

Farmland prices have made double-digit gains since 2005 save during parts of recession-racked 2008, The New York Times reported.

A Federal Reserve Bank of Chicago survey finds that prices rose by 15 percent over a year in parts of Iowa, Illinois, Indiana, Wisconsin and Michigan, The Times noted, adding that other Fed studies reveal prices across a swathe of the Great Plains rose by 26 percent last year.

Editor's Note: 'It’s Curtains for the US' — Hear Unapologetic Warning from Prophetic Economist.

Poor returns in stock and bond markets and low interest rates are chasing investors to alternative assets such as farmland.

“What’s a C.D. at the bank? Half a percent,” Clark Wadle, who attended a farmland auction, told the newspaper.

“What’s the stock market? Unstable. Whether land prices go up or they go down again, you still have the property.”

Others warn that a bubble might be brewing.

“Any time you have an asset that doubles in value over a decade, there is cause for concern about how sustainable that growth is,” Richard Brown, chief economist at the FDIC, said.

Commodities bull and noted investors Jim Rogers has said farming will become a good investment over the long term.

Demand for food will rise as big emerging economies like China and India grow and bring millions out of poverty, while supplies will come under strain due in part to aging farmers poised to retire.

“There are many ways to invest in agriculture. The best is to become a farmer,” Rogers told Moneynews TV in May.

”You can buy farmland, you can invest in seed companies, fertilizer companies, tractor companies — there are many ways to invest in agriculture.”

Investors shouldn’t limit themselves to U.S. markets either.

”You can invest in agricultural countries — Canada is more agriculturally oriented than we are. So is Australia. There are plenty of ways to invest in agriculture. The best way is to become a farmer or to invest in agriculture products.”

Editor's Note: 'It’s Curtains for the US' — Hear Unapologetic Warning from Prophetic Economist.