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By HYONHEE SHIN
Capital News Service
LANSING – Lawn fertilizer may be threatening lakes, not feeding the grass.
Some lawmakers are seeking to protect streams and lakes from runoff contamination by restricting phosphorus lawn fertilizer use.
Under the bill by Rep. Terry Brown, D-Pigeon, property owners wouldn’t be able to use lawn fertilizers containing phosphorus unless a soil test concludes the existing level of phosphorus is too low or they’re growing new turf.
Allegan, Ottawa, Muskegon, Van Buren, Bay and Saginaw counties have adopted a ban, as has Ann Arbor, according to the Department of Agriculture. Similar ordinances have been adopted by Battle Creek, Novi, Ferrysburg, East Grand Rapids and Cannon, Bloomfield, Spring Lake and Pittsfield townships, among other localities.
Michigan State University Extension offices offer a soil test for about $8, Brown said. If the test verifies the need for phosphorus fertilizers, property owners could use it for three years under the proposal.
Brown said phosphorus may cause water pollution.
“When you overfertilize a lawn with phosphorus and there’s leftover on driveways, where does it go? That gets washed away with rain down into sewers, then out to rivers, streams and lakes, and it’s polluting,” said Brown.
Charles Bauer, an analyst with the Department of Environmental Quality (DEQ) Water Bureau, said most soils in Michigan have sufficient phosphorus to support turfgrass growth.
“In some cases, additions of phosphorus are needed but generally not,” said Bauer. “Most homeowners don’t test their soil to determine whether phosphorus addition is needed and likely are overapplying it if they use standard phosphorus fertilizer mixes.”
Bauer said the primary hazard of phosphorus fertilizers is that they often end up on impervious surfaces such as sidewalks and driveways where direct runoff occurs.
“When phosphorus gets into the water, it’s like fertilizing the river and you boost growth of aquatic plants,” he said. “This can lead to a nuisance condition in our rivers and lakes.”
Kevin Frank, an Extension turfgrass specialist in Michigan State University’s Crop and Soil Sciences Department, said simple practices such as sweeping or blowing fertilizer back onto the lawn can minimize such risks.
“Phosphorus is an essential nutrient required for plant growth and development, especially during establishment,” he said. “I don’t perceive the proper use of phosphorus-containing fertilizers as a hazard.”
However, Frank’s primary concern is homeowners who apply complete fertilizers containing high phosphorus levels.
“In these instances, the amount of phosphorus is mostly excessive,” Frank said. “If a soil test is taken on whether phosphorus is needed, any risk of applying phosphorus when not necessary would be eliminated.”
April Hunt, bulk storage and fertilizer program manager with the Department of Agriculture, said the use of such fertilizers could be reduced.
“I don’t think it’s being used too abundantly, but excessive phosphorus fertilizers may cause problems with water and algae blooms. Not just fertilizer, but phosphorus itself could be harmful to organism in general,” said Hunt.
Concern with excess nutrient runoff has led a number of municipalities and counties to ban or restrict phosphorus fertilizers, but the effectiveness of such laws had been an open question until a University of Michigan study on the bans’ impact.
Researchers found that phosphorus levels in waterways dropped by an average of 28 percent over two years after Ann Arbor prohibited the use of phosphorus on lawns in 2006.
Janis Bobrin, Washtenaw County water resources commissioner, said she’s seen a significant reduction in phosphorus concentrations in the Huron River since the city ordinance took effect.
“Additional analysis is being performed to determine more about the relationship between the ordinance, water quality improvement and other variables, but the ordinance is undoubtedly a factor,” Bobrin said.
She said the Middle Huron Watershed is under a federal mandate to reduce phosphorus levels in its waterways by 50 percent, and reducing lawn care chemicals will be important in achieving that target.
Bans on phosphorus fertilizers have been imposed throughout the country. Minnesota in 2004 became the first state to enact a statewide restriction. In Florida, statewide restrictions went into effect in 2008.
Hunt, at the Agriculture Department, said about 4,000 kinds of zero-phosphorus fertilizers are available.
Joe Rathbun of the DEQ Water Bureau said Brown’s bill would measurably lower the amount of phosphorus getting into water bodies.
“The point is not to ban all fertilizer use, just the excessive use,” Rathbun said. “The trick is to not use more fertilizer than is necessary to maintain a healthy lawn, plus follow other practices of environmentally friendly lawn care – keep grass clippings, don’t use more herbicide or insecticide than is absolutely necessary and cut grass high enough to tolerate dry spells.”
Dave Dempsey, a board member of the Alliance for the Great Lakes and communication director for Conservation Minnesota, a Minneapolis-based nonprofit organization, said phosphorus fertilizers do more harm than good in most situations.
“If Michigan is serious about protecting the Great Lakes, it should enact a statewide ban on the sale of phosphorous lawn fertilizers. Minnesota has done so and lawns are still green in the summer,” said Dempsey, a former environmental advisor to ex-Gov. James Blanchard.
Co-sponsors include Reps. Daniel Scripps, D-Leland; Fred Miller, D-Mount Clemens; Gabe Leland, D-Detroit; Ellen Cogen Lipton, D-Huntington Woods; Tim Bledsoe, D-Grosse Pointe; Marie Donigan, D-Royal Oak; Sarah Roberts, D-St. Clair Shores; and Mark Meadows, D-East Lansing.
The bill is pending in the House Great Lakes and Environment Committee.
© 2009, Capital News Service, Michigan State University School of Journalism. Not to be reproduced without permission.