The tumbleweed: a vagabond energy crop

They're a common sight out here in the West, skittering across dusty, endlessly stretching hihways. Soon, those bouncing balls of spiny tumbleweed may be common- place somewhere else -- in your fireplace.

Within just a few years, Salsoli kali L.m -- as the pesky weed is known to its more intimate scientific ac quaintances -- may be burning on hearths across the country in the form of "tumblelogs."

Under a project begun a little over a year ago, University of Arizona researchers have already harvested and compressed their first crop of tumbleweeds. In their final form the logs look like -- and burn about as well as -- the compressed sawdust logs you can now buy from your local grocer.

Research associate Martin Karpiscak predicts it will be one to three years before the logs will be marketed at a competitive price.And eventually those involved with the project plan to experiment with tumble pellets as an alternative energy source for small-scale industrial use.

But the project's most important impact may be an economic one. An estimated 20 percent of Arizona's 1.3 million acres of agricultural land has been abandoned because water -- a crucial and hardly plentiful Arizona resource -- is either too expensive or simply no longer available.

What Mr. Karpiscak and his colleagues hope is that tumbleweed may put some of that land back in business. Hardy, and a lot less thirsty than crops like alfalfa and wheat, tumbleweeds grow almost anywhere -- particularly in soil which has been "disturbed" or previously dug up.

In addition, the tumbleweed is actually an exotic plant. introduced here by mistake over 100 years ago, the weed hails from Russia and Pakistan, where -- for better or worse -- virtually all of the plant's natural enemies have remained.

The trick, however, is learning the best method for cultivating a plant which in the past, Mr. Karpiscak says, has been nothing more than "a troublesome weed, basically."

For their first crop, university researchers harvested wild weeds -- one of which was so large (over five feet tall and seven feet in diameter) that it would make four five-pound tumblelogs. In contrast, it may take as many as 25 more modest-size tumbleweeds to create just one log.

"We're turning a pest into a potential energy source," says Mr. Karpiscak. "And that's going to take awhile. You just don't create a new agricultural crop overnight."