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November 2000 Issue

Oxygen-Poor 'Dead Zone' Links Gulf of Mexico with Minnesota Waters

Not all jubilees are celebrations. Some are natural phenomena that warn of trouble in the environment.

When a jubilee erupts off the Louisiana coast, crabs, shrimp and fish swarm near shore, trying to escape oxygen-deficient water. Aquatic creatures that can't escape succumb to hypoxia (oxygen deprivation), and many die. Those only stunned may recover, if tides or winds change, pushing oxygen-poor water into the Gulf of Mexico's depths.

Jubilees occur in coastal areas around the world, as a result of excessive nutrients (particularly nitrogen) flowing from rivers into oceans. Last year, an oxygen-depleted zone in the Gulf covered 5,800 square miles, roughly the size of New Jersey.

Unfortunately, Minnesota contributes its share of nutrients to Gulf of Mexico jubilees - 7 percent of the nutrients robbing the Gulf of oxygen arrive via the Mississippi River from Minnesota, bringing the problem very close to home.

The nutrients destroying aquatic life down south also degrade water quality in our own back yards. Nitrate exceeds Minnesota's health-based drinking water standards in 3 percent of wells, according to a 1998 statewide survey. Worries about nitrate in ground water confront communities in southeastern Minnesota, including Mankato and Rochester. Phosphorus stimulates algae blooms and oxygen depletion in state waters, threatening fishing, swimming and environmental diversity. Eroded soil clogs transportation waterways like the Mississippi River, leading to costly and destructive dredging.

"As the headwaters state, Minnesota will be watched for leadership in reducing nutrient loads on the state's waters," says MPCA Assistant Commissioner Gordon Wegwart, member of the U.S. Department of Commerce National Oceanic and Atmospheric Administration's federal task force on hypoxia for two years. "We already are reducing pollutants to the Mississippi, because it's in our own best interests."

How nutrient-rich water robs the Gulf of oxygen

The annual discharge into the Gulf, via the Mississippi and Atchafalaya rivers, is 1.5 million metric tons of nitrogen. This is the primary culprit causing hypoxia. An estimated 68 percent of the nitrogen originates as agricultural runoff, but other causes include urban runoff, lawn fertilization, wastewater plants and airborne sources.

The nutrient-rich water promotes explosive algae growth. This initially increases production of sea life. But as more algae grow, die and sink to the bottom, their decomposition depletes oxygen in deeper water, especially at times of the year when oxygen is not easily replenished in the lower depths. Fish, shrimp and crabs flee the dead zone, and less mobile species suffocate.

The Gulf fishery nets annual catches of more than 1 billion pounds. Trawlers operate on the edges of the hypoxic zone or travel farther from shore to net their catch. Gulf commercial fishers are concerned about their businesses
and futures.

Fishermen, farmers linked by the mighty Mississippi

The tie that binds Midwestern farmers with those who farm the Gulf is the Mississippi River.

The last half-century saw great gains in farm productivity. The state's average per-acre corn yield climbed from 39.5 bushels in 1950 to 150 in 1999. To obtain such high yields, farmers fertilize generously. Each year, farmers apply 110-160 pounds of nitrogen per acre to soils that naturally provide at least 115 pounds. Manure application adds more nitrogen. The extra nitrogen drains into the Mississippi via smaller rivers and streams.

According to University of Minnesota scientist David Mulla, land in the Blue Earth, Le Sueur and Lower Minnesota watersheds of the Minnesota River contribute the lion's share of 68,250 tons of nitrogen flowing to the Gulf each year from Minnesota. "The nitrogen yields to the Minnesota River from the Le Sueur watershed are an average of 25 pounds per acre per year, as high as those from any other watershed in the Mississippi River Basin," Mulla says.

Other changes to Minnesota land increase the Gulf-bound flood of nutrients. Each year, farmers install drainage lines on 250,000 acres, siphoning off usable nitrogen. Landowners also drain prairie potholes and wetlands, features that can hold
60-90 percent of the nitrogen from field runoff, preventing it from flowing into waterways.

Other Upper Midwestern Corn Belt states mirror the picture here. Mulla explains: "As an area of extensive row-crop agriculture, fertilizer may be applied in the fall or at higher-than-recommended rates. Soils are high in organic matter and often artificially drained. Mean annual precipitation is 30 to 50 inches. All these factors make for heavy nitrogen loads in Minnesota waters."

Call to action at the federal level

In 1998, the U.S. Congress enacted the Harmful Algal Bloom and Hypoxia Research and Control Act, aiming at two consequences of nutrient overload: hypoxia and harmful algae. The law:

• Established a federal task force on hypoxia, which includes MPCA Commissioner Karen Studders;
• Commissioned an assessment on hypoxia's ecological and economic consequences;
• Required a plan to control hypoxia in the Gulf by March 30, 2000 (see the draft plan at http://www.epa.gov/msbasin/fr-actionplan.html.)

The action plan has three long-term goals:

• Protect the waters of the 31 states and tribal lands in the Mississippi basin and their aquatic life.
• Improve management of public and private lands using a cooperative, incentive-based approach.
• Reduce nitrogen inputs to the basin by 20-40 percent by 2010.

"Just one more thing on my plate"

Hypoxia can be reversed. The tactics seem simple: reduce nitrogen inputs from all sources (including urban runoff and wastewater treatment plants) and restore ecosystems that remove nutrients before they reach rivers and streams. The implications, however, are far from simple, particularly for farmers.

Agriculture is a tough business, prey to fluctuating prices, competition and unpredictable weather. To protect the environment, farmers carefully consider pesticide use, comply with feedlot regulations, protect wetland areas, and reserve productive land along lakes and rivers. Now, they are being asked to reduce fertilizer use. Many are willing to do so - voluntarily.

"Numerical standards, such as the 30 percent nitrogen reduction that's been proposed for the Mississippi River basin, are controversial," says Mulla, who believes it's too early to set a numerical goal. Numbers raise concerns about regulation, even if they are goals (something to shoot for) rather than requirements. Numerical goals clearly define a desired outcome and allow policymakers to track progress. The path to achieve them matters most, and substantial agreement exists about that.

"All members of the task force, some other states in the basin, and farmers in general are supportive of incentive-based and voluntary approaches to nutrient reduction," says Wegwart.

The Minnesota Way

Minnesota's challenge is to devise a sensible solution to reduce the state's share of nitrogen. Initial efforts will be designed to dovetail with other state water-pollution goals, such as ground-water protection, phosphorus reduction, habitat restoration and erosion control. Though the point-source and agricultural assistance programs will get the most attention, all Minnesotans will be encouraged to reduce nitrogen use and runoff for cleaner water here and downstream.

Strategies include:

• Minnesota Conservation Reserve Enhancement Program (CREP), a 1998 initiative to encourage landowners to take an estimated 190,000 acres of land out of use for 15 years. Landowners receive incentive payments and a cost share for conservation practices. (The CREP combines the federal Conservation Reserve Program and the state's Reinvest in Minnesota to accomplish its long-term goals.) See the Minnesota Board of Water and Soil Resources (BWSR) web site for details at http://www.bwsr.state.mn.us/programs/major/crep/.
  
  
• Minnesota River Basin Plan. State, regional and local governments and citizens groups, including the 37-county Minnesota River Basin Joint Powers Board, are bringing floodplain and river restoration, best management practices, and pollutant-specific solutions to each tributary and watershed in the basin. Read about the basin at http://www.pca.state.mn.us/water/basins/mnriver/index.html.
  
  
• Clean Water Partnerships match motivated local groups with funding and technical experts from the state to solve local water- quality problems. For more information, visit the MPCA web site at http://www.pca.state. mn.us/water/cwpartner.html.
  
  
• Nitrogen Fertilizer Management Plan, an initiative stimulated by the 1989 Groundwater Protection Act, focuses voluntary and regulatory action on reducing nitrogen fertilizer in the state's waters. For information, access the Minnesota Department of Agriculture site at http://www.mda.state.mn.us/DOCS/usefulnutrmgmtdata.pdf.
  
  
• Water Pollution Control Revolving Fund provides federal dollars for water pollution projects, including runoff control, conservation tillage, erosion control, buffer zones and wetlands reconstruction. For information, go to http://www.pca.state.mn.us/water/revolvingfund.html.
  
  
• Feedlot Control Program reduces the nitrogen impacts of animal waste. New feedlot rules passed in August 2000 will help alleviate feedlot runoff. For information, go to http://www.pca.state.mn.us/hot/feedlots.html.

When we learn to make the connection between miles of cold, oxygen-starved Gulf water and Minnesota's rivers, aquifers, fields and urban concrete - that may merit a real jubilee.

- Sam Brungardt

Farmers reduce nitrogen use -- and still get good crops

Research demonstrates that more isn't necessarily better

If a little fertilizer is good for crops, more is even better, right? Not necessarily, says research showing that farmers can reduce the use of nitrogen fertilizer and still get high crop yields. "The message to growers is that with proper nitrogen management they can see some cost savings, get good crop yields, and help protect the environment," says Bruce Montgomery, Minnesota Department of Agriculture.

One study found that reducing nitrogen fertilizer by half ? from 160 to 80 pounds per acre ? cut nitrogen runoff from 32 to 21 parts per million (ppm). Another project showed that planting grass on fallow land reduced nitrogen runoff from 20 ppm to as low as 2 ppm. "This indicates how a grass cover can cannibalize the nitrogen in the soil," said Gyles Randall, University of Minnesota Southern Research and Outreach Center at Waseca.

On a test plot at Red Top Farm near St. Peter, Rob and Janice Meyer demonstrated similar results. Applying nitrogen fertilizer in spring at a 110-pound per acre rate instead of 160 reduced nitrogen losses by up to 50 percent. "I've found that by using precision-farming methods, I can apply half as much nitrogen as before ... and still achieve equal, if not better, yields," Rob told "The Furrow" magazine.

- Forrest Peterson

Watershed thinking harvests rewards beyond nitrogen reduction

Intensive one-on-one landowner education results in nitrogen drop of up to 50 pounds an acre

It's one thing to set goals for reducing nitrogen use, but another to get results on a large scale. A southeastern Minnesota project in the Zumbro River watershed proved it could be done - and models voluntary methods of success.

The Olmsted County Hydrologic Unit Area (HUA) Project shows that intensive landowner education improves nitrogen management and reduces leaching and runoff. The HUA, launched in six townships surrounding Rochester in 1991, covered a 138,240-acre area. The goal: protect groundwater quality in the St. Peter-Prairie du Chien aquifer (used as a drinking water supply in the area) by promoting improved land-management practices. Project sponsors and partners included the Natural Resources Conservation Service, Farm Service Agency, University of Minnesota Extension Service, MPCA, Olmsted Soil and Water Conservation District, Olmsted County and the City of Rochester.

Awareness among participants of environmental matters increased, and 90 percent of those surveyed reported implementing changes such as integrated pest management, conservation tillage, contour strips and nutrient management plans. Other outcomes:

• Only 4 percent of survey respondents tested livestock manure for nutrient content in 1991. This increased to 72 percent by 1998.
• Less than 15 percent knew the application rate of manure applied per acre in 1991. More than 70 percent of respondents knew their application rate in 1998.
• More than 100 nutrient management plans were written for farmers, covering more than 26,000 acres.
• Sixty-five percent of respondents in 1998 reduced their nitrogen application rate by at least 50 pounds an acre on fields fertilized with manure.
• Farmers learned that manure could replace commercial fertilizer needs and save them an average of $50 per acre.

- Norman Senjem