BISMARCK (AP) -- A rich but untapped potash deposit in northwestern North Dakota is being eyed by mining companies looking to fill a growing global demand for the fertilizer, the state geologist says.
"We always knew this deposit would be of interest and that it was just a matter of waiting for the right economic conditions," geologist Ed Murphy said.
"Really, what's pushing this is India and China need more fertilizer," Murphy said.
Wen-Yuan Huang, an economist with the federal Agriculture Department, said global demand for potash has spiked in the past decade but supply has been flat.
"It's pretty much a global commodity now," Huang said. "The market is very strong, especially in China."
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The demand for potash, a form of potassium, has increased in the U.S. largely to grow more corn, which is used for ethanol production, Huang said.
"It's very new in the last 10 years in China and other poor countries that put potash in the soil," Huang said. "It has a tremendous effect on yields."
North Dakota's vast potash beds, created by oceans that dried up some 400 million years ago, cover about 11,000 square miles the northwestern corner of the state, Murphy said.
Nearly 90 percent of the potash used for domestic crop production comes from mines in western Canada, the U.S. Geological Survey says. Some of the biggest mines in Canada are less than 150 miles north of North Dakota, Murphy said.
The Canadian and North Dakota deposits are contiguous, though the potash in Canada is found at shallower depths, and is easier to recover, Murphy said.
Canadian potash beds, which supply most of world demand, are about 5,000 feet beneath the surface; North Dakota's potash deposit ranges from 5,600 feet to about 12,000 feet underground, Murphy said.
Potash is found beneath Divide, Bottineau, Renville, Burke, Dunn, Williams, Mountrail, Ward and McKenzie counties, Murphy said. The shallowest depth it occurs is in western Bottineau County, northern Renville County and eastern Burke County, he said.
"It would be getting the same potash out of the same rocks as Canada, but you just have to drill a little deeper here," Murphy said.
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Potash, sometimes mixed with other salts, is recovered by traditional mining and by solution mining, a process that involves injecting liquid in holes to dissolve and recover it.
Advanced drilling techniques learned from the oil industry could help cheaply reach the potash at North Dakota's deeper depths, Murphy said.
"Oil and gas technology is readily applicable to this," he said.
Geologists estimate that North Dakota holds some 50 billion tons of potash, 10 billion tons of which could be recovered economically, Murphy said.
About 2 million tons of potash could be recovered annually in North Dakota using solution mining, or nearly double the amount of potash produced domestically each year, Murphy said.
Huang said 8 million tons of potash was imported in 2007, while only 1.2 million tons came from U.S. mines.
The USGS says only three states produce potash: Utah, New Mexico and Michigan.
Murphy said mining companies, which he would not name, have been studying core samples from North Dakota's potash beds. At present, no company has applied for a mining permit, he said.
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Potash mining likely would be welcomed in northwestern North Dakota, where jobs and people are scarce.
"It's an area of the state where there isn't a whole lot of industry other than oil and gas," Murphy said. "You wouldn't have to bring in too many jobs to have an impact on the economy."
Companies considered mining North Dakota potash in the 1970s, but believed it to be too deep to recover economically at the time, Murphy said.
"They went to Michigan, instead," he said.
