It is a well–known fact that turf grass possesses many qualities that improve the environment and plays a critical role in urban environment and ecosystems.
A recent Review of the Environmental Benefits of Turf sources scientific evidence from Australia and overseas and provides a comprehensive list of the many environmental benefits of turf grass. These include benefits to the atmosphere, land, water as well as many others.
Atmosphere quality benefits
Turf grass like all other plants uses carbon and light to undergo photosynthesis. Energy for the growth of turf grass is generated from this process and oxygen is released into the environment as a byproduct.
As turf grass is so abundant, particularly in urban and suburban environments, it plays an important role in maintaining our air quality by generating oxygen.
Carbon sequestration and sinks
Turf grass can be used to mitigate climate change as it has the potential to capture and store carbon, known as carbon sequestration. Turf grass absorbs carbon dioxide (CO) as an input for photosynthesis, which reduces carbon in the atmosphere and releases oxygen.
Appropriately maintained turf grass can sequester carbon at a rate that makes it a net carbon sink. In other words turf grass can capture convert and store carbon in the soil than is produced to maintain it. (i.e.) mow, irrigate and fertilise).
Open turf spaces not only reduce noise and glare; they also act as a fire barrier and significantly lower the ground surface temperature on hot summer days.
Recent studies from the United States suggest that turf can sequester an average of 1.2 tonne of carbon per hectare, per year for as much as 30 to 40 years. Some studies suggest this figure might be substantially higher, depending on the climate and maintenance regime in place.
Dust prevention and stabilisation
Dust (particles of soil or other matter small enough to be moved and carried by the wind) can have a harmful impact on human health by aggravating asthma and eczema conditions and also contributes to environmental problems such as water pollution and sedimentation.
Turf grass captures and suppresses dust by slowing the wind velocity allowing dust to settle as well as preventing dust particles from becoming dethatched and airborne in the first place. Dust particles that are caught by turf grass are moved via rainfall to become part of the living soil system.
Air pollution control/air quality improvement.
Air pollution is the atmosphere of chemicals, particulate matter or other materials that cause harm to humans or other animals. Air pollution can have serious human health implications and can lead to incidences od respiratory, heart and lung diseases which are estimated to contribute to two million deaths world wide every year. Air pollution can also have serious environmental impacts.
Including ozone depletion, increased concentrations of greenhouse gases, ocean evapotranspiration. It can also control many types of air pollution by capturing and processing pollutants, smoke, dust and dirt particles from the atmosphere and entraps them into the soil using grass blades.
Water quality benefits
Turf grass provides an excellent covering for roadside verges. New low maintenance and drought tolerant varieties may only require mowing twice a year and watering for establishment.
Water filtration and purification
Water is an essential resource needed to maintain all life on earth. Turf grass can reduce the degradation of water quality by slowing down runoff and trapping pollutants, sediments and heavy metals, preventing them from leaching into adjacent water bodies.
Water purification occurs when water is leached through the turf grass root zone and into underground aquifers or when it is run over grassed areas as the leaves tap suspended solids and sediments material.
Turf grass is also used in industries such as food processing as methods of cleaning wastewater before it is discharged into natural water bodies (a type of phytoremediation). Some turf grass types have a very high tolerance of salt, chemicals and nutrients and are suitable to use to dispose of lower quality waters such treated sewerage and some mining wastewaters.
Water run-off reduction
If runoff is not controlled, it can contain pollutants, chemicals and pesticides, which may lead to eutrophication and contamination of adjacent, water bodies (lakes, rivers, and or streams), which can damage or kill aquatic plants and animals.
Areas of turf grass play a significant role in reducing water runoff and can retain vast quantities of water. Storm water runoff from a healthy, dense area of turf grass can be at or near zero, meaning that virtually all runoff is estimated.
Generally speaking, runoff and pollution created by an area of turf grass, is far less than that from a hard surface or bar ground area.
Rainwater harvesting and entrapment- ground water recharge
Rainwater harvesting or entrapment refers to collecting rainwater and surface runoff from roofs or other catchment surfaces, where it is stored for future use.
Turf grasses are capable of preserving and trapping runoff and rainwater in the soil due to their growth habitat; dense plant can plant canopy biomass matrix and earthworm activity. In turn, this this reduces excess runoff and results in more water for infiltration into the soil. The dense plant canopy of mowed turf can act as a “sponge’ by absorbing vast amounts of water which increases the rate of groundwater recharge. This can reduce the occurrence and the ferocity of flash flooding by allowing infiltration of the water into the soil which is not possible in impermeable, hard surfaces such as concrete, paving or asphalt.
Land quality benefits
Reduction in nutrient movement and loss
Sediment and nutrients runoff can occur from water running of bare areas of earth, construction sites and exposed cultivated areas. This can lead to serious negative environmental effects such as autotrophication of water bodies, habitat loss, dissolved oxygen loss leading to fish kills and reduction in water clarity.
Healthy turf grass systems have the ability to absorb the majority of nutrients applied to it as fetiliser and can minimise the amount, which is leached, or runoff. Turf grasses have a strong and expansive root system, which can enhance the entrapment and uptake of essential nutrients such as nitrogen (N) phosphorous (P) and therefore minimise the potential of eutrophication in local waterways.
Turf grass is a very effective, cheap and durable form of erosion control due to its dense root system, which readily and quickly binds to the soil (see Breakout Box). Turf grass has the potential to reduce on-site and off-site erosion and sediment pollution runoff by providing two main functions to alleviate erosion potential, including acting as a buffer strip to trap sediment and runoff and by providing surface protection to reduce sediment detachment in the first instance.
TURF GRASS IS A VERY EFFECTIVE, CHEAP AND DURABLE FORM OF EROSION CONTROL DUE TO ITS DENSE ROOT SYSTEM WHICH READILY AND QUICKLY BINDS TO THE SOIL.
Turf grass has been found to be more effective than many other control treatments such as silt fences and coir logs.
Turf controls erosion due to its high shoot density, root mass and high biomass matrix which provides protection from raindrop impact soil stabilization and resistance to lateral surface water flow.
Research had found that in all turf tested the turf root system binds with the soil sufficiently within eight days to be secure and resist any tunneling under the turf slabs- even under heavy flows
Turf grass can be used for erosion control on high gradients and reducing water flow (and power) allowing fir the trapping and controlling of sediments.
Soil improvement and restoration
Turf grass has a vital function in the restorstion of envirnmentally damaged lands and soils. Turf grass can help restore damaged soils such as those effected by fire, erosion, mining, harvest and lanfill areas.
Turf grass like other plants is constantly creating new topsoil from decompsing roots, stems and leaves. Soil improvement can occour using turf grases thjrough thr addtion of organic matter from composting (turnover) of organic maatrial such as roots and plant tissue throgh photosynthesis.
As the plant tissue dies, it is incorporated into the root system and turned over into the soil. A high propotion of fertile soils are often developed under a vegetative grass cover such as that of turf grass. Calculations within the research suggest that as the plant tissue dies, it is incorprated into the root system whch is turned over at an annnual rate od 42 percent, meaning that about 6761 kilograms per hectare of root biomass is turned into the soil each year.
Fertile soils are often develpoed or improved under a vegetative grass cover such as turf, because water is captured and allowed to infiltate into the soil providing a less hostile enviroment for soil microorganisms.
Bioderadation of synthetic organic compounds (phytoremediation)
Turf supports a large, diverse population of soil microorganisms, microflora and microfauna and earthworms. Compared to grassland, the average microbial bomass is 42 cenr less for cropland and 29 per cent less for forest.
These measurements were made on non-irrigated grasslands therefore, many irrigated turf grass areas are likely to have even larger microbial populations. These species are supported by and cause the decomposition of, roots and shoots and play an important role in the ecological process of degradation of animall wastes, organic chemicals/materials, noxious chemicals and pesticides into neutralised or harmless substances.
The turf grass soil ecosystem with its large microorganism population offers one of the most active biological systems for degraduation of trapped organic chemicals and pesticides, thereby functioning in the protection of soils and groundwater quality. Turf has the ability to assist in phytoremediation of contaminated land areas including salt affected as well as oil, chemical and heavy metal contaminated land.
Alleviating heat island effects
The urban heat island phenomenon is often measured by the temperature difference recorded between the city center and rural surroundings or suburban areas, with surface and air temperatures being recorded as much higher in built-up city areas than in rural areas.
Excessive warmth in urban areas can be attibuted to the use of surface dark materials such as asphalt and roofing, reduced vegetation and by the high solar radiation absorbance of urban surfaces or 'hardscape' elements of urban landscape. These three factors contribute to the warming of the air in urban areas, thereby producing a heat island effect.
An independent economic analysis was undertaken and examined two scenarios.
In both scenarios the cost of a common alternative was compared to that of turf as well to the combination of both measures. In the housing development of scenario 1, a 2m wide turf buffer zone was compared to a silt/sediment fence both of which ran around the perimeter of the property.
In scenario 2, full turf coverage of the verge was compared to a hydro mulch alternative and the cost of combining of both was also calculated.
Under Scenario 1 ‘turf only’ as a treatment option the cheapest being 8 per cent and 9 per cent cheaper than silt fencing at the low and high values respectively.
The combination of using two sediment and erosion control measures was, as expected, the most expensive treatment option. Note that the cost of turf grass was scheduled as zero as it was assumed it would be laid as part of the eventual landscaping and therefore only established and maintained costs during the build were allocated to the turf options.
In Scenario 2, hydro mulch was the most inexpensive option in three of four possible price combinations, being between 15 and 46 per cent cheaper than turf strip alone. However, a turf strip in the drain apex becomes the optimal option. Turf strips in this instance are 13 per cent cheaper than hydro mulch. As seen in Scenario 1, using a combination of both measures was more expensive than using a single measure alone.
It should be noted, however that this is based purely on a cost comparison and does not take into account the erosion. The effectiveness of measures in controlling sediments and soil large fines for failure to install appropriate measures, it may be a false economy to use a substandard or ineffective control method in place of turf just because it is ‘less expensive’.
Research shows that appropriately installed turf requires only eight days to be secure and resist Tunneling.
Turf grass reduces temperature in two ways; the first is by providing shade of heat-absorbing surfaces and the second through the process of evapotranspiration, which dissipates high levels of radiant energy in urban areas and provides a cooling effect.
Vegetated surfaces (including green roofs) are cooler than non-vegetated surfaces. Shaded vegetated surfaces can also provide for even greater cooling and then reduce the reliance on artificial cooling from air conditioning.
In a pilot study conducted in Australia researches tested the temperature differences between green and hard landscape surfaces namely turf grass, mulch gravel, artificial turf, paving and concrete. Turf was shown to have the lowest daily average temperatures compared to all other types with artificial turf commonly reaching a temperatures of well over 60°C.
In another Australian study conducted in the mid-summer with an air temperature recording of 40°C the surface temperature of turf grass as 45.65°C compared to dark concrete which was record at 78.27°C. Related to these measurements was the ability to absorb, hold and radiate heat through the early evening. Turf was able to cool quicker than all of the other materials by utilizing its natural cooling mechanisms while other hard surfaces held and radiated heat well into the evening.
Noise and glare reduction
Turf grass can successfully reduce noise and glare in urban environments and has been shown to control sound levels as its rough surface characteristics absorb, deflect and refract various unwanted noises. Turf grass also has a far greater success rate of abating harsh sounds than surfaces such as bare round or pavement.
One US study found that an area of 21m of turf grass near a roadside can abate vehicle noise by up to 40 per cent. Additionally, the surface of turf can reduce glare as it reflects light in different directions, which lowers the harshness and stress of light in bright conditions on the human eye.
Turf can act as a buffer zone of grass around buildings, which helps to retard the spread of fires and as a vital firebreak. It also serves as a high visibility zone, which can make the advent of fire more obvious.
In a climate like Australia, annual bushfires present a real threat to people, property, communities and natural areas. Strategic areas of turf can help protect housing developments and townships by acting as a buffer between bush land and high priority buildings and zones to assist firefighters with access. Turf can also slow or halt fire as it sweeps through an area.
Table 1: Summary of the environmental benefits of turf grass.
• Air pollution control/air quality improvement
• Oxygen generation
• Dust prevention and stabilisation
• Carbon sequestration and sink
• Water filtration and purification (phytoremediation)
• Water runoff reduction and entrapment
• Rainwater harvesting and entrapment –ground water recharge
• Reduction in nutrients movement and loss
• Erosion control
• Soil improvement and restoration
• Biodegradation of synthetic organic compounds (phytoremediation)
• Alleviating heat island effects
• Noise and glare reduction
• Fire prevention
• Biodiversity and ecosystem\services
Biodiversity and ecosystem services
Properly designed urban landscapes, which incorporate turf, can provide wildlife habitat and promote animal and plant diversity. Turf grass provides an essential habitat and breeding ground for certain fauna species which are critical for maintaining a balanced ecosystem and have potential value as an area of conservation for native wildlife and threatened species of birds, frogs, mammals and reptiles. Much of the literature refers to the benefits of golf courses in urban areas. One study from US found turf grass ecosystems can be home to more than 100 taxa including insects, beetles, earthworms, nematodes and other invertebrates.
Over 12 verifiable environmental benefits of turf grass have been proven. This includes improving the quality of our atmosphere, water, and land as well as providing biodiversity and an ecosystem in an urban environment.