Continuing Education and
Communication Services
3614 Administrative Services Building
Ames, Iowa 50011-3614
(515) 294-9915
9/19/01
Contacts:
John Downing, Department of Animal Ecology, (515) 294-2734, downing@iastate.edu
John Creswell, Nutrient Management Education Project, (515) 727-0656,
creswell@iastate.edu
Del Marks, Continuing Education and Communication Services, (515) 294-9807,
delmarks@iastate.edu
FOR IMMEDIATE RELEASE
Iowa Water Quality Affected by Use of Phosphorus Fertilizers
AMES, Iowa -- Water quality in Iowa has been a hot topic this past summer, according to researchers at Iowa State University. At the heart of the discussion have been farm and lawn fertilizers and especially the nutrient phosphorus (P).While it is completely normal for some phosphorus to exist in Iowa waters, the levels of P that now exist in Iowa are some of the highest in the world. That is neither normal nor healthy, said John A. Downing, professor of aquatic ecology at ISU.
High levels of phosphorus contribute to a condition called eutrophication. "It's really the 'over-fertilization of aquatic systems' that we're talking about," Downing said. "Abundant P generates unnaturally vigorous algal growth, or 'algae blooms.' Algae blooms cause a myriad of water quality problems, including the removal of life-sustaining oxygen from the water. When algae blooms occur, 'eutrophic' systems begin to break down and lose much of their value to people and to nature."
Downing said farmers can help by using practices that reduce phosphorus in surface waters. "Minimizing soil erosion as well as cutting nutrient loss by reducing tillage trips or going to no-till, soil testing and limiting P application only to soils where soil tests indicate a need all help can make a big difference. Buffers, grass waterways, terraces, erosion control, contour farming and other erosion control systems also limit P losses to surface waters."
Healthy aquatic systems not only indicate healthy landscapes, they are economically important as well. One of the negative impacts of eutrophication is the unpleasant smell of decomposing algae, impairing the recreational use of water. Downing estimates that Iowa lakes generate more than $20,000 per lake-acre, per year; significant benefits of good water quality to Iowa and local communities.
Where to go from here? Downing said, "We know that eutrophication is a sign of an unhealthy aquatic system, but that it can be prevented by controlling the amount of P getting into the water. Farmers can reduce P levels in water by using best management practices such as soil testing and applying P only when indicated and by using conservation or no-tillage to reduce soil erosion."
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