WEST LAFAYETTE, Ind. -- Purdue University research is helping farmers choreograph a balancing act with phosphorus, giving plants and livestock just enough of the nutrient so they grow properly, but no more.
That's important because excess phosphorus can find its way into surface water, where it causes algal blooms and fish kills and hastens the aging process in lakes.
Part of Purdue's role has been to identify the problem. The next step is to help farmers use phosphorus efficiently.
U.S. researchers knew years ago that excess phosphorus in rivers could cause trouble, but they thought most of it came from urban and industrial waste, not farm fields.
"Even 10 years ago the prevailing thought was that phosphorus in fields didn't move, unless it eroded away with soil," says Purdue agronomist Brad Joern.
Phosphorus already has been banned from detergents and laundry soaps. But enough phosphorus was still making its way into streams last fall to warrant federal attention. An Oct. 18, 1997, message from Vice President Al Gore directed the Environmental Protection Agency to "identify the major sources of nitrogen and phosphorus in our waters, and identify actions to address these sources."
Even before federal eyes turned back to phosphorus, Purdue researchers suspected that old theories about the nutrient's movement weren't accurate. In 1992, Joern started measuring phosphorus levels in fields and found that phosphorus can move down through soils.
"Fields with a long history of phosphorus loading from manure or other fertilizer sources can lose phosphorus in surface water runoff and potentially even through tile drains three feet down," Joern says. From there it can be a quick trip to a neighboring river or lake.
Joern and colleagues from Michigan and Ohio are developing a set of new environmental
guidelines that should keep phosphorus out of surface water while still giving good
crop yields. The guidelines will tell producers
Contact: Rebecca Goetz