Lawn
2008/9 Schools Wikipedia Selection. Related subjects: Recreation
A lawn is an area of recreational or amenity land planted with grass, and sometimes clover and other plants, which are maintained at a low, even height.
Usage
Lawns are a standard feature of ornamental private and public gardens and landscapes in much of the world today. Lawns are created for aesthetic use in gardens, and for recreational use, including sports. They are typically planted near homes, often as part of gardens, and are also used in other ornamental landscapes and gardens.
Lawns are frequently a feature of public parks and other spaces. They form the playing surface for many outdoor sports, reducing erosion and dust as well as providing a cushion for players in sports such as football, cricket, baseball, golf, tennis, bocce and stake. In sports venues, the word lawn is often replaced by turf, pitch, field or green depending on the sport and the locale.
Many different species of grass are used, often depending on the intended use of the lawn, with vigorous, coarse grasses used where active sports are played, and much finer, softer grasses on ornamental lawns, and partly on climate, with different grasses adapted to oceanic climates with cool summers, and tropical and continental climates with hot summers. It is also not uncommon to mix grass seeds. A 50/50 mixture of grass types can, for example, form a stronger lawn when one grass type does better in the warmer seasons and the other is more resistant to colder weather.
History
Before the invention of mowing machines in 1830, lawns were managed very differently. Lawns belonging to wealthy people were sometimes maintained by the labour-intensive methods of scything and shearing—in most cases, however, they were pasture land which was maintained through grazing by sheep or other livestock. Areas of grass grazed regularly by rabbits, horses or sheep over a long period often form a very low, tight sward similar to a modern lawn. This was the original meaning of the word "lawn", and the term can still be found in place-names. Some forest areas where extensive grazing is practiced still have these semi-natural lawns. For example, in the New Forest, England, such grazed areas are common and are known as lawns, for example Balmer Lawn.
Lawns became popular in Europe from the Middle Ages onward. The early lawns were not always distinguishable from pasture fields. It is thought that the associations with pasture and the biblical connotations of this word made them attractive culturally. By contrast, they are little-known or used in this form in other traditions of gardening. In addition, the damp climate of maritime Western Europe made them easier to grow and manage than in other regions.
It was not until the Tudor and Elizabethan times that the garden and the lawn became a place to be loved and admired. Created as walkways and for play areas, the lawns were not as we envisage them today. They were made up of meadow plants, such as camomile, a particular favourite. In the early 1600s the Jacobean epoch of gardening began. It was during this period that the closely-cut "English" lawn was born. By the end of this period, the English lawn was the envy of even the French; it was also seen as a symbol of status by the gentry. In the early 1700s, gardening fashion went through a further change. William Kent and the age of Capability Brown were in progress, and the open "English" style of parkland was seen across Britain and Ireland. Lawns seemed to flow from the garden into the outer landscape.
During Victorian times, as more plants were introduced into Britain and the influence of France and Italy became prevalent, lawns became smaller as borders were created and filled with plants, statues, sculptures, terraces and water features, which started encroaching onto the area covered by the lawn. In the United States, it was not until after the Civil War that lawns began to appear outside middle-class residences. Most people did not have the hired labor needed to cut a field of grass with scythes; average home owners either raised vegetables in their yards or left them alone. If weeds sprouted that was fine. Toward the end of the 19th century, suburbs appeared on the American scene, along with the sprinkler, greatly improved lawn mowers, new ideas about landscaping and a shorter workweek.
Lawns do not have to be, and have not always been, made up of grass alone. Other plants for fine lawns in the right conditions are camomile and thyme. Some lawns, if grown in difficult conditions for grasses, become dominated by whatever weeds can survive there; these include clovers in dry conditions, and moss in damp shady conditions. In more recent times, especially in suburban residential areas, a lawn may refer to an area surrounding a home where some or all of the natural grass or sod has been removed and replaced with artificial turf, stones, mulch, or some other material determined by the homeowner to reduce maintenance and/or water consumption.
Criticisms
A number of criticisms of lawns are based on environmental grounds:
- Many lawns are composed of a single species of plant, or of very few species, which reduces biodiversity, especially if the lawn covers a large area. In addition, they may be composed primarily of plants not local to the area, which can further decrease local biodiversity.
- Lawns are sometimes cared for by using synthetic pesticides and other chemicals, which can be harmful to the environment, especially when misused.
- Consequently, in Canada, for example, over 140 municipalities and the entire province of Quebec have now placed restrictions on the cosmetic use of synthetic lawn pesticides as a result of health and environmental concerns. The Ontario provincial government promised on September 24, 2007 to also implement a province-wide ban on the cosmetic use of lawn pesticides, for protecting the public. Medical and environmental groups support such a ban. On April 22, 2008, the Provincial Government of Ontario announced that it will pass legislation that will prohibit, province-wide, the cosmetic use and sale of lawn and garden pesticides. The Ontario legislation would also echo Massachusetts law requiring pesticide manufacturers to reduce the toxins they use in production. The Province of Prince Edward Island is also considering such legislation. On April 3, 2008, the Canadian Cancer Society released opinion poll results conducted by Ipsos Reid, which established that a clear majority of residents in the provinces of British Columbia and Saskatchewan want province-wide cosmetic lawn pesticide bans, and that the majority of respondents believe that cosmetic pesticides are a threat to their health.
- Sweden, Denmark, Norway, Kuwait and Belize have also placed restrictions on the use of the herbicide 2,4-D.
- The use of pesticides and synthetic fertilizers, which require fossil fuels to be manufactured, has been shown to be detrimental to combating global warming, whereas organic techniques help reduce global warming. See: Rodale Institute
- Maintaining a green lawn sometimes requires large amounts of water. This was not a problem in temperate England where the concept of the lawn originated, as natural rainfall was sufficient to maintain a lawn's health. However the exporting of the lawn ideal to more arid regions of the world, such as the U.S. Southwest and Australia, has crimped already scarce water resources in such areas, requiring larger, more environmentally invasive water supply systems. Grass typically goes dormant during cold, winter months, and turns brown during hot, dry summer months, thereby reducing its demand for water. Many property owners consider this "dead" appearance unacceptable and therefore increase watering during the summer months. Grass can also recover quite well from a drought.
- In the United States lawn heights are generally maintained by gasoline-powered lawnmowers, which contribute to urban smog during the summer months. The U.S. Environmental Protection Agency found that in some urban areas, up to 5% of smog was due to pre-1997 small gasoline engines such as are typically used on lawnmowers. Since 1997, the EPA has mandated emissions controls on newer engines in an effort to reduce smog.
However, using ecological techniques, the impact of lawns can sometimes be reduced. Such methods include the use of local grasses, proper mowing techniques, leaving grass clippings in place, integrated pest management, organic fertilizers, and introducing a variety of plants to the lawn.
In addition to the environmental criticisms, some gardeners question the aesthetic value of lawns.
One positive benefit of a healthy lawn is that of a filter for contaminants and to prevent run-off and erosion of bare dirt. Highway construction projects in the United States now routinely include replanting grasses on disturbed soils for this purpose, although they are not maintained as lawns. It is important to note that a healthy lawn does not necessarily mean that synthetic pesticides need to be used, as organic solutions exist.
Popularity in the United States
In a recent NASA-sponsored study, researcher Christina Milesi estimated the area covered by lawns in the United States to be about 128,000 square kilometers (nearly 32 million acres), making it the nation's largest irrigated crop by area. Lawn care is thus a major business in the United States; maintenance, construction and management of lawns of various kinds being the focus of much of the modern horticulture industry. Estimates of the amount spent on professional lawn care services vary, but a Harris Survey put the total at $28.9 billion in 2002 (approximately $1,200 per household using such services).
In her book The Lawn: A History of an American Obsession (1994) Virginia Scott Jenkins traces the historic desire to kill weeds. She notes that the current rage for a chemically-dependent lawn emerged after World War II and argues that "American front lawns are a symbol of man's control of, or superiority over, his environment."
Approximately 50-70% of American residential water is used for landscaping, most of it to water lawns.
Along with trees, lawns are a vital element in the fight against urban heat islanding. Lawns provide:
- Oxygen conversion,
- Filtering of air particulates,
- Erosion control,
- Air and surface cooling to offset asphalt, cement, and rooftops.
- A place for children to run around and play games.
In comparison to bare dirt, a lawn may be 20° (Fahrenheit) cooler on a hot day, and up to 40° cooler than cement surfaces.
Maintenance
Maintaining a rough lawn requires only occasional cutting with a suitable machine, or grazing by animals.
Maintaining higher quality lawns may require special maintenance procedures:
- Mowing regularly with a sharp blade at an even height.
- Not mowing when lawn is wet.
- Not removing more than 30% to 40% of the plant tissue.
- Alternating the direction of cut from previous mowing.
- Scarifying and raking, to remove dead grass and prevent tufting.
- Rolling, (to encourage tillering (branching of grass plants) and to level the ground).
- Top dressing with sand, soil or other material.
- Spiking or aeration (to relieve compaction of the soil).
- Additional watering.
- Fertilizing application.
- Organic or synthetic pesticide application.
It must be noted that there is often heavy social pressure to mow one's lawn regularly.
Seasonal lawn maintenance
Seasonal lawn care will vary to some extent depending on the climate zone and type of grass that is grown, whether cool season or warm season varieties. In general, however, there are recognized steps in lawn care that should be observed in any of these areas.
Spring or early summer is the time to seed, sod, or sprig a yard, when the ground is warmer. For a new lawn, adding a fresh load of topsoil to the ground is beneficial. Seeding the lawn is the least expensive way to plant, but it takes longer for the lawn to grow and usually needs daily watering, or the freshly-sprouted grass will die. Sodding is more expensive, but it will provide an almost instant lawn that can be planted in most climate zones in any season. Hydroseeding is a relatively quick and inexpensive method of planting. A nitrogen-based, slow-release fertilizer may be applied, when needed. Pesticides, which is an umbrella term that include herbicides, insecticides and fungicides, may be considered for use on lawns when required, and where legal. In Canada, over 130 municipalities and the province of Quebec prohibit the use of synthetic lawn pesticides . Although synthetic pesticides exist, organic solutions are increasingly being used. For example, corn gluten meal controls weed seeds by releasing an organic dipeptide into the soil and inhibiting root formation of germinating weed seeds. An application of beneficial nematodes can be used to combat grubs.
Summer lawn care requires raising the lawn mower for cool season grass, and lowering it for warm season lawns. Lawns will require longer and more frequent watering, best done in early morning to encourage a stronger root system. This is also the time to apply an all-purpose fertilizer. During the hot summer months, lawns may be susceptible to fungus disease. It’s advisable to take a sod sample to a local landscape expert for testing and treating the yard, if necessary.
In the autumn, lawns can be mowed at a lower height and thatch buildup that occurs in warm season grasses should be removed, although lawn experts are divided in their opinions on this. This is also a good time to add a sandy loam and apply fertilizer, one that contains some type of wetting agent. Cool season lawns can be planted in autumn if there is adequate rainfall.
Lawn care in the winter is minimal, requiring only light feedings of organic material, such as green-waste compost, and minerals to encourage earthworms and beneficial microbes.
Types of lawngrass
There are thousands of varieties of lawngrass, each adapted to specific conditions of precipitation, temperature, and sun/shade tolerance. Breeders are constantly creating new and improved varieties of the base list of lawngrass species. The two basic categories are cool season grasses and warm season grasses.
Cool season grasses start growth at 5 °C, and grow at their fastest rate when temperatures are between 10-25 °C (Huxley 1992), in climates that have relatively mild/cool summers, with two periods of rapid growth in the spring and autumn. They retain their colour well in extreme cold and typically grow very dense, carpetlike lawns with relatively little thatch.
- Bluegrass
- Bentgrass
- Ryegrasses
- Fescues
Warm season grasses only start growth at temperatures above 10 °C, and grow fastest when temperatures are between 25 °C and 35 °C, with one long growth period over the spring and summer (Huxley 1992). They often go dormant in cooler months, turning shades of tan or brown. Many warm season grasses are quite drought tolerant, and can handle very high summer temperatures, although temperatures below -15 °C can kill most warm season grasses.
- Zoysiagrass
- Bermudagrass
- St. Augustine grass
- Bahiagrass
- Centipedegrass
- Carpetgrass
- Buffalograss
- Grama grass