Study: Phosphorous overused, running out

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MADISON, Wis., Feb. 14 (UPI) -- U.S. researchers say world stocks of phosphorous, a fertilizer vital to agriculture, are low but its overuse has become a leading cause of water pollution.

Scientists at the University of Wisconsin-Madison report the human use of dwindling supplies of phosphorous, primarily in the industrialized world, is causing widespread eutrophication, or algae "blooms" in fresh surface water, a university release said Monday.

Excess phosphorous from fertilizer that washes from farm fields and suburban lawns into lakes and streams is the primary cause of the blooms that throw freshwater ecosystems out of kilter and degrade water quality, Stephen Carpenter, a UW-Madison professor of limnology, says.

"Phosphorous stimulates the growth of algae and weeds near shore and some of the algae can contain cyanobacteria, which are toxic, Carpenter says. "You lose fish. You lose water quality for drinking."

Agricultural practices to conserve phosphate more effectively within agricultural ecosystems are necessary to avert the widespread pollution of surface waters, he argues.

This is especially important, Carpenter says, as minable global stocks of phosphorous are concentrated in just a few countries and are in decline, posing the risk of global shortages within the next 20 years.

"There is a finite amount of phosphorous in the world," says. "This is a material that's becoming more rare and we need to use it more efficiently."