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Fertilizers and the Health of Aquatic Systems - Organic Trade Association
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Fertilizers and the Health of Aquatic Systems

 

Because organic agriculture respects the balance of microorganisms in the soil, organic producers use composted manure and other natural materials, as well as crop rotation, to help improve soil fertility, rather than petroleum-based synthetic fertilizers that can result in an overabundance of nitrogen and phosphorous in the ground. As a result, organic practices help protect ground water supplies and avoid runoff of chemicals that can cause "dead zones" in larger bodies of water.

  • "Organic farming can help reduce ground and surface water contamination, and can safeguard drinking water supplies in certain areas, thus contributing to food safety in a larger sense and sustainable agriculture."
    Source: "Food Safety and Quality as Affected by Organic Farming," 22nd FAO Regional
    Conference for Europe, Porto, Portugal, July 24-28, 2000, Agenda Item 10.1.

  • Farm comparisons in Europe have shown nitrate leaching rates on organic farms are 40-57% lower per hectare and carbon dioxide emissions are 40-60% lower per hectare than conventional systems, according to a comprehensive European-wide literature review.
    Source: "Environmental and resource use impacts of organic farming in Europe," by Stolze, Piorr, Haring and Dabbert, 2000.

    On the other hand, current conventional practices have led to some measurable problems:

  • Research performed at Oak Ridge National Laboratory’s Environmental Sciences division revealed that hypoxia, a fatal condition that affects thousands of fish, shrimp, and shellfish in the Gulf of Mexico each year, is partly the result of fertilizer run-off from agricultural activities in the Mississippi basin.  The run-off, along with the temperature differentials created when the warm water from the Mississippi and Atchafalaya Rivers come into contact with the cold Gulf waters, forms a deadly combination whereby algae grows, dies, decomposes and uses up the oxygen the aforementioned organisms need for survival. To combat this problem, and reduce phosphorus production, which is also seen as a contributing factor in the rise of hypoxia, researchers have proposed increasing the use of environmentally sustainable biofuel, improving nutrient management, and restoring wetlands in the affected areas. 
    Source: http://www.newswise.com/articles/view/539988/

  • According to research performed by Tufts University biologists, tadpoles experienced negative physiological changes, including deformed hearts and malfunctioning kidneys and digestive systems, in early phases of their lives when they were exposed to atrazine, an herbicide commonly used to treat golf courses and residential lawns.  While causation had not yet been conclusively determined, researchers found that “compared with control populations, the tadpoles that were exposed to atrazine had a dramatically higher incidence of abnormalities.” 
    Source: http://www.newswise.com/institutions/view/?id=1939

  • Research at the NOAA National Centers for Coastal Ocean Science has show negative effects of the commonly used herbicide atrazine on phytoplankton, the free-floating algae that form the base of the food chain for aquatic animals. Results, published in January 2007 in the journal Pesticide—Biochemistry and Physiology, showed protein levels in phytoplankton decreased as a result of exposure to atrazine.
    Source: Pesticide—Biochemistry and Physiology, January 2007

  • Pesticide residues are widely found in U.S. streams, according to data for 1992-2001 released in March 2006 by the U.S. Geological Survey (USGS). “More than 80 percent of urban streams and more than 50 percent of agricultural streams had concentrations in water of at least one pesticide that exceeded a water-quality benchmark for aquatic life,” the study found. USGS analyzed 51 major river basins and aquifer systems as well as the aquifer system in the High Plans. The pesticides chlorpyrifos, azinphos-methyl, p,p'-DDE and alachlor were most commonly found in agricultural streams at concentrations that might affect aquatic life. USGS also said that most stream samples and about half of the well samples contained two or more pesticides. Because potential total toxicity may be greater with pesticide mixtures, USGS recommended that studies of mixtures should be a high priority.
    Source: U.S. Geological Survey, “Pesticides in the Nation’s Streams and Ground Water, 1992-2001,” http://pubs.usgs.gov/circ/2005/1291/.

  • The United Nations in February 2006 released a report entitled “Challenges to International Waters: Regional Assessments in a Global Perspectives,” resulting from the Global International Waters Assessment project. Noting “pressures from human activities have weakened the ability of aquatic ecosystems to perform essential functions,” the report looked at freshwater shortage, pollution, over-fishing, habitat modification, and global change. Pointing out that oxygen-depleted zones are present not only in enclosed seas such as the Baltic and Black Seas but also in large coastal areas, the report states, “Globally, harmful algal blooms are considerably more widespread and frequent than they were a decade ago, a situation that is expected to further deteriorate by 2020 due to the increased application of agricultural fertilizers, especially in Asia and Africa.” The project also found that reduced stream flow inappropriate irrigation practices and use of groundwater “have increased the salinity of freshwater throughout the world. As a result, agricultural land is becoming too saline to support important crops.” The report recommends an integrated approach linking water management to land and economic management.
    Source: www.giwa.net/publications/finalreport/.

  • Nitrates in drinking water are statistically associated with an increased risk of bladder cancer at levels lower than the U.S. EPA standard of 10 parts per million (ppm), according to a University of Iowa Study of almost 22,000 women. Long-term heavy use of nitrogen fertilizers in Iowa has resulted in nitrate concentrations in excess of 5 ppm in 30-40 percent of the state’s municipal water supplies, according to a study published in Epidemiology. Peter Weyer of the University of Iowa’s Center for Health Effects of Environmental Contamination, and colleagues analyzed cancer incidences in women participating in the Iowa Women’s Health Study, and found that women drinking water with average nitrate levels greater than 2.46 ppm were 2.83 times more likely to develop bladder cancer than women exposed to 0.36 ppm of nitrates in water.
    Source: Epidemiology, Vol. 11(3): 327-338, May 2001.

  • The report "Waste Lands: The Threat of Toxic Fertilizer" noted that many commercial fertilizers contain toxic metals. An analysis of 29 fertilizers found that each contained 22 different heavy metals. In 20 of the products, levels exceeded the limits set on wastes sent to public landfills, with disturbing quantities of arsenic, lead, mercury, cadmium, chromium, and dioxin, among others.
    Source: "Waste Lands: The Threat of Toxic Fertilizer," U.S. Public Interest Research Group, May 2001, available at www.pirg.org/toxics/reports/wastelands.

  • A 2001 report has found that polluted runoff from farms and cities went largely unabated or actually increased over the past 30 years. The report notes that many of the nation’s coastal environments exhibit symptoms of over-enrichment. Symptoms include algal blooms (some of which may be toxic), loss of sea grasses and coral reefs, and serious oxygen depletion. As a result, coastal regions see reduced production of valuable fisheries, threats to biodiversity, and ecosystems less resilient to natural and human influences.
    Source: "Marine Pollution in the United States: Significant Accomplishments, Future Challenges," review led by Dr. Donald Boesch from the University of Maryland Center for Environmental Science, Pew Oceans Commission, 2001.

  • "The principal nutrient of concern in coastal waters is nitrogen. Our use of commercial fertilizer and combustion of fossil fuels has had a dramatic effect on the global nitrogen cycle. U.S. coastal ecosystems are receiving one hundred to four hundred percent more nitrogen than natural systems would experience…Ninety percent of the nitrogen pollution that contributes to the ‘dead zone’ in the Gulf of Mexico is discharged to tributaries in the Mississippi and Ohio River watersheds from farms and cities located north of St. Louis, MO."
    Source: Testimony of the Honorable Eileen Claussen, president and chair of the board, Strategies for the Global Environment, and member, Pew Oceans Commission, before the Subcommittee on Fisheries Conservation, Wildlife and Oceans, House Committee on Resources, May 24, 2001.

  • Nearly all crops grown in industrialized countries are exposed to more nitrogen than they can use. Too much nitrogen can throw the soil community out of balance, and also lead to algal blooms in water that suffocate other aquatic organisms. In fact, algal blooms and "dead zones" are now regular features of coastal life in many places around the world.
    Source: "Toxic Fertility," by Danielle Nierenberg, WorldWatch, March/April 2001, pages 30-38.

  • Researchers at Iowa State University (ISU) are concerned over water quality in Iowa, particularly with the high levels of phosphorus due to the use of farm and lawn fertilizers. Phosophorus levels in Iowa are some of the highest in the world, according to John A. Downing, professor of aquatic ecology at ISU, noting that this contributes to eutrophication, or algae blooms.
    Source: Iowa State University Extension press release, Sept. 21, 2001.

  • Nitrogen delivery to the Gulf of Mexico could have been reduced 33 percent between 1960-1998 if the use of nitrogen-containing fertilizer in the Mississippi Basin had been cut by 12 percent, according to Gregory F. McIsaac, Mark B. David, George Z. Gertner, and Donald A. Goolsby.
    Source: Brief Communications, Nov. 8, 2001, issue of Nature (pages 166-167).

  • The increasing use of commercial fertilizers could be contributing to global warming by decreasing oxygen and raising levels of nitrous oxide in coastal waters, according to scientists at the National Institute of Oceanography in India. Their findings, published in the Nov. 16, 2000, issue of Nature, found nitrous oxide levels in the coastal Arabian Sea that are 100 times greater than normal levels.
    Source: Nature, Nov. 16, 2000.


The Organic Trade Association is the leading business association representing the organic industry in the United States, Canada, and Mexico. Its 1700 members include growers, processors, shippers, retailers, certification organizations and others involved in the business of producing and selling certified organic products.

© 2008, Organic Trade Association.

 
 
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