Eutrophication is a syndrome of ecosystem responses to human activities that fertilize water bodies with nitrogen (N) and phosphorus (P), often leading to changes in animal and plant populations and degradation of water and habitat quality. Nitrogen and phosphorus are essential components of structural  cell membranes, nucleic acids, and  molecules that capture and utilize light and chemical energy to support life. The biologically available forms of N and P are present at low concentrations in pristine lakes, rivers, estuaries, and in vast regions of the upper ocean.

Pristine aquatic ecosystems function in approximate steady state in which primary production of new plant biomass is sustained by N and P released as byproducts of microbial and animal <!– Create this article: metabolism –>metabolism. This balanced state is disrupted by human activities that artificially enrich water bodies with N and P, resulting in unnaturally high rates of plant production and accumulation of organic matter that can degrade water and habitat quality. These inputs may come from untreated sewage discharges, <!–Add this page: sewage–>sewage treatment plants or runoff of fertilizer from farm fields or suburban lawns. In some cases the climax stage of algal blooms can release toxic chemicals such as domoic acid to the aquatic environment, creating elevated metabolic risks to a variety of fish and marine mammals.

Eutrophication was first evident in lakes and rivers as they became choked with excessive growth of rooted plants and floating algal scums, prompting intense study in the 1960′s-70′s and culminating in the scientific basis for banning phosphate detergents (a major source of P, the most frequent culprit in eutrophication of lakes) and upgrading sewage treatment to reduce waste water N and P discharges to inland waters. Symptoms of eutrophication in estuaries and other coastal marine ecosystems (where N is the most frequent contributor to eutrophication) were clearly evident by the 1980′s, as human activities doubled the transport of N and tripled the transport of P from Earth’s land surface to its oceans. Eutrophication has emerged as a key human stressor on the world’s coastal ecosystems.

Nutrient enrichment of marine waters promotes the growth of algae, either as attached multicellular forms (e.g. sea lettuce) or as suspended microscopic phytoplankton, because algae can grow faster than larger vascular plants. Small increases in algal abundance or biomass have subtle ecological responses that can increase production in food webs sustaining fish and shellfish, even producing higher fish yields. However, over-stimulation of algal growth leads to a complex suite of interconnected biological and chemical responses that can severely degrade water quality and threaten human health and sustainability of living resources in the coastal zone.

Modern high-yield agriculture, golf courses, parks and urban gardeners presently use commercial fertilizers in large quantities – substances that became cheap to produce in the mid 20th century – the era in which N and P concentrations began to increase in surface waters carrying agricultural and urban runoff to the sea. The world’s human population is growing disproportionately in the coastal zone, creating an additional challenge of reducing nutrient inputs from municipal waste, septic systems, and fertilizer runoff from lawns and gardens. Projections indicate that the largest future increases in N and P delivery to the coastal ocean will occur in eastern and southern Asia where populations and economies are growing most rapidly.

The eutrophication problem illustrates how human activities on land can degrade the quality of coastal waters and habitats, with potentially large economic and ecological costs. Solutions to the coastal eutrophication problem require changes in all these activities within the watersheds and airsheds connected to coastal waters. Commitments to these solutions are now beginning – the European Union’s Water Framework Directive mandates strategies to reduce N and P delivery to coastal waters, and a 2000 National Research Council report recommended a National Coastal Nutrient Management Strategy for the United States.

The Author

Tukey noted that many plants commonly considered weeds can help organic gardeners diagnose nutrient deficiencies in their lawns. Correcting these deficiencies by organic means can then improve the health of the overall lawn and eliminate the weeds.

“Some weeds tell you your lawn is acidic,” Tukey said. “Some weeds tell you your lawn is compacted. Some weeds tell you it’s too wet.”

Other weeds actually correct nutrient deficiencies. Clover, for example, adds nitrogen to the soil. In the mid-twentieth century, clover seed was regularly mixed in with grass seed for this very purpose, said Mike Goatley of Virginia Tech university.

“We’re coming full circle,” Goatley said.

Sources for this story include:http://www.csmonitor.com/The-Cultur….

Learn more:http://www.naturalnews.com/029722_lawn_care_organic.html#ixzz1F1JGLBv8

Lawn chemicals are unnecessary. Historically, organic lawn care has been practiced for much longer than chemical lawn care and it can easily be implemented on any lawn. Safe and effective alternatives exist for most chemical pesticides and fertilizers. There is no need to expose our families, communities and local wildlife to chemicals that are known or potential hazards.

Chemical pesticides and fertilizers contaminate surface and groundwater. Lawn pesticides and fertilizers can contaminate surface and groundwater. This diminishes the quality of our drinking water as well as the quality of aquatic habitats and health of aquatic life forms. Many fish and aquatic insect species are highly sensitive to fertilizers and pesticides.

Chemical pesticides threaten the health of children. 
Children are the most vulnerable segment of our population due to their small size and their underdeveloped physiology. Children are also often the most exposed to pesticides due to their behavior (putting contaminated grass, soil and toys into mouth, breathing close to the ground). Increased exposure puts children at an unacceptably high risk from lawn pesticides.

Chemical pesticides threaten the health of outdoor pets. 
Outdoor pets are highly exposed to lawn chemicals due to their behaviour (licking contaminated paws and coat, breathing close to the ground, eating contaminated grass, soil and toys) and are highly vulnerable due to their small size.

Chemical pesticides threaten the health of local wildlife. Turf-dwelling and feeding species such as the American robin, Canada goose, American widgeon, European starling, common raccoon and eastern gray squirrel are highly exposed to lawn chemicals. Granular formulations pesticides can severely impact birds that mistake the granules for seed or other food items.

Chemical pesticides and fertilizers reduce the activity of beneficial organisms. 
Healthy soil is alive with a variety of beneficial organisms that actually kill pest insects, decrease the spread of disease and help plants gather nutrients and water. For example, earthworms improve air and water circulation, decompose thatch, deposit nutrient-rich castings and help to neutralize soil (plants prefer this pH). Many of these beneficial organisms are highly exposed and highly sensitive to lawn chemicals. Pesticides and fertilizers reduce their activity levels, thereby reducing a lawn’s natural ability to control pests and diseases, gather nutrients and water and maintain overall health.

Local wildlife need safe places to live. As more and more suburbs encroach upon natural habitats, wildlife are forced to flee or adapt to less ideal, often crowded habitats ripe with potential dangers. Exposure to lawn chemicals is one such danger. Direct exposure to these pesticides and fertilizers is dangerous, as are the effects of chemical use including decreased shelter and food opportunities. We can make our cities and towns more habitable for local wildlife by avoiding lawn and garden chemicals. You may even consider naturalizing a section of your yard to provide a greater diversity of shelter and food types.

Chemical fertilizers are a waste of money. Chemical fertilizers usually contain three macronutrients – phosphorus, potassium and nitrogen. They lack other macro as well as micronutrients and include no organic matter or microbes. In contrast, finished compost from your backyard bin is an organic and natural soil amendment that provides a more complete package of nutrients, organic matter and microbes. Finished compost is a free resource that also constitutes sustainable waste management, extending the lifespan of local dumps and landfills.

Chemical pesticides have the potential to cause damage throughout their lifecycles. 
All stages of a pesticide’s lifecycle – production, transport, storage, use and disposal – have the potential to degrade environmental and human health. Explosions, spills and volatilization may occur in manufacturing plants, storage facilities and en route, exposing potentially huge numbers of non-target organisms to pesticides. Disposal is an expensive and controversial proposition as people campaign to keep stockpiles out of their communities.

Chemicals actually degrade the over-all long-term health of your lawn and garden. Chemical lawn care is the wrong approach. By frequently applying pesticides to your lawn, you may create a chemical-dependent landscape. As pest species become resistant to the chemicals designed to kil them, more concentrated doses and frequent applications are required and a never-ending cycle of increasing pest resistance and pesticide use is established. When this happens, your lawn’s health is spiraling downhill.

Burgeoning restrictions on water use, fertilization, and pesticide application are becoming important considerations in golf course design and management. In response, scientists are searching for sustainable methods to lessen the environmental impact of golf courses. Other factors, including increasing energy costs, human health concerns, and environmental awareness are also prompting turfgrass managers to consider the use of alternative turfgrasses as a lower input, sustainable maintenance practice. A new study published in HortScience identified four alternative turfgrass species—two bentgrasses and two fescues—as promising for use as low-input fairways.

In the cool-season region of the United States, golf course managers traditionally grow creeping bentgrass on putting greens and favor Kentucky bluegrass, creeping bentgrass, or perennial ryegrass for fairways. When used on fairways, however, these species require significant amounts of inputs such as nitrogen fertilization, irrigation, and pesticides. A sustainable, effective strategy to deal with potential risks associated with these inputs may be the use of alternative turfgrass species. The challenge is finding low-input turf that can survive and perform adequately under conditions of little or no supplemental irrigation, high traffic, no pesticides, and reduced fertility.

Eric Watkins, Andrew B. Hollman, and Brian P. Horgan of the Department of Horticultural Science at the University of Minnesota designed a research study that tested alternative turfgrass species not currently used for golf course fairways in the northern U.S. In 2005, 17 species of turfgrass were established on native soil in St. Paul. Each species was evaluated at three levels of traffic (zero, three, or six passes per week using a drum-type traffic simulator) and two mowing heights (1.90 and 2.54 cm).

In 2006, velvet bentgrass (Agrostis canina L.), colonial bentgrass (Agrostis capillaris L.), and creeping bentgrass (Agrostis stolonifera L.) maintained acceptable quality in all treatment combinations. In 2007, Chewings fescue (Festuca rubra L. ssp. fallax) and sheep fescue (Festuca ovina L.) were the top-performing species regardless of treatment. Hard fescue (Festuca brevipila Tracey) performed poorly the first year of the study, but performed well in the second year. The other species evaluated in the study did not perform at acceptable levels.

The test results indicated that sheep fescue, Chewings fescue, colonial bentgrass, and velvet bentgrass should be studied further for use on low-input golf course fairways in the northern U.S. “In this study, the fine fescue species showed the greatest potential for use on low-input golf course fairways. To our knowledge, this is the first report of sheep fescue being a successful fairway turf in the United States”, noted Watkins. The research demonstrates that alternative cool-season turfgrass species may be able to perform adequately on golf course fairways under low-input conditions in Minnesota and similar areas.

The study findings may hold great promise for turfgrass professionals, but will the new grasses prove popular with golfers? According to Watkins, researchers in the United Kingdom acknowledged high levels of support for increased biodiversity among golf course superintendents, but found that there were conflicts between the golfers’ preferences and the needs of conservation plans that promote biodiversity. “Similarly, we expect that resistance from golfers to new grass species may limit the use of low-input species on golf course fairways.”

More information: The complete study and abstract are available on the ASHS HortScience electronic journal web site: http://hortsci.ash … act/45/1/113

Provided by American Society for Horticultural Science