Posted Monday, Sept. 27, 2010
Full Report (9-page PDF)
News Release (below) (2-page PDF)
IOWA CITY, Iowa (September 27, 2010) — Farm practices are the central source of applied pollutants in Iowa waterways, and policy measures need to focus on agriculture, Iowa researchers say.
“We need to get past people trying to shift our focus to smaller sources of pollution. Our central challenge to clean water in Iowa is, without question, our agricultural practices,” said David Osterberg, executive director of the nonpartisan Iowa Policy Project (IPP) and a former chair of the Iowa House Agriculture Committee. “Iowa policy makers must not allow themselves to be distracted.”
The new report from IPP provides background on nutrient pollution in the Mississippi River Drainage Basin, estimates the sources of nutrient pollution for Iowa, and discusses fertilizer application timing and ground cover. Those issues affect whether the nutrients are used as intended, to increase crop yield, or become unhealthy and costly water pollution, IPP researchers said.
“The data are clear: Fertilizers applied for crop production in Iowa are the leading cause of nutrient pollution in our state’s rivers and streams,” said IPP Research Associate Will Hoyer, a co-author of the report. “Of course we always must consider all sources of water pollution and there are problems that come from our cities, towns and even rural lawns.
“But the main culprits are nitrogen and phosphorus that are applied to agricultural land. That is where state environmental policy must focus, because the problems will remain unless we address this.”
The researchers said steps are being taken to reduce pollution from both rural and urban settings.
“What is being done now is not enough. Pollution is outpacing current approaches,” Hoyer said. “We need new rules to require, or incentives to encourage, better practices. Strategies must consider the planting of cover crops, nutrient testing, conservation tillage and adherence to well-developed nutrient-management plans.”
The report looked at application of nutrients — nitrogen and phosphorus — for various land uses:
An estimated 96 percent of nitrogen applications went to corn ground, and about 2 percent to soybean fields. Less than 2 percent of nitrogen was applied to residential lawns or golf courses.
About 86 percent of phosphorus applications were to corn ground, and almost 12 percent to soybean fields, with less than 2 percent applied to residential lawns or golf courses.
“While on average, households and golf course operators apply both nitrogen and phosphorus at greater rates per acre, their impact is minimal due to the small amount of acreage receiving applications,” according to the report for IPP by Andrea Heffernan, Teresa Galluzzo and Hoyer.
The researchers noted that nitrogen and phosphorus have important positive qualities for raising crops, but cause environmental process when applied in excess — not only locally, but beyond.
“American farmers take great pride, as they should, in their production of food for people all over the world,” Hoyer said. “But we need the same attention to the side effects of these efforts: Pollution doesn't remain only in local waters. The excess nutrients being applied in the upper Midwest, for example, have created an acutely toxic problem in the Gulf of Mexico.”
The report noted that the United States Geological Survey (USGS) has found agriculture to be the dominant source of nutrient delivery to the Gulf of Mexico, estimating that ag sources contribute more than 70 percent of the delivered nitrogen and phosphorus to the Gulf.
According to USGS, Iowa and eight other states contribute 75 percent of the nitrogen and phosphorus delivered to the Gulf — though the nine states account for less than one-third of the Mississippi River watershed area. For nitrogen alone, Illinois and Iowa generate over 28 percent of the nitrogen reaching the Gulf, but have only 9 percent of the watershed.
“The pollution coming from Iowa farm fields dwarfs that coming from Iowa lawns and golf courses. We should not ignore other contributors, but the state’s water quality problems are first and foremost the result of the way agriculture is currently practiced in Iowa. We cannot hide that fact,” Hoyer said.
The Iowa Policy Project is a nonpartisan, nonprofit public policy research organization in Iowa City. IPP reports on environment and energy, economic opportunity and budget and tax issues are at www.iowapolicyproject.org.