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 (CO2) 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 more carbon in the soil than is produced to maintain it (i.e. mow, irrigate and fertilise). 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 detached and airborne in the first place. Dust particles that are caught by turfgrass are moved via rainfall to become part of the living soil system.
Air pollution control/air quality improvement
Air pollution is the release into 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 of respiratory, heart and lung diseases which are estimated to contribute to two million deaths worldwide every year. Air pollution can also have serious environmental impacts including ozone epletion, increased concentrations of greenhouse gases, ocean acidification and plant injury.
Turf grass can reduce smog pollution through the process of 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
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 trap suspended solids and sediment material. Turf grass is also used in industries such as food processing as a method 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 salts, 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. Stormwater runoff from a healthy, dense area of turf grass can be at or near zero, meaning
that virtually all runoff is eliminated. Generally speaking, runoff and pollution created by an area of turf grass, is far less than that from a hard surface or bare 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 canopy, biomass matrix and earthworm activity. In turn, 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 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 nutrient runoff can occur from water running off bare areas of earth, construction sites and exposed cultivated areas. This can lead to serious negative environmental effects such as eutrophication 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 fertiliser 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) and phosphorous (P) and therefore minimise the potential of eutrophication in local water ways.
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 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 stabilisation and resistance to lateral surface water flow. Research has found that in all turf varieties 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 for reducing water flow (and power) allowing for the trapping and controlling of sediment.
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.
Soil improvement and restoration
Turf grass has a vital function in the restoration of environmentally damaged lands and soils. Turf grass can help restore damaged soils such as those affected by fire, erosion, mining, harvest and landfill areas. Turf grass like other plants is constantly creating new topsoil from decomposing roots, stems and leaves. Soil improvement can occur using turf grasses through the addition of organic matter from composting (turnover) of organic materials such as roots and plant tissues through photosynthesis. As the plant tissue dies, it is incorporated into the root system and turned over into the soil. A high proportion 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 incorporated into the root system which is turned over at an annual rate of 42 per cent, meaning that about 6761 kilograms per hectare of root biomass is turned into the soil each year. Fertile soils are often developed or improved under a vegetative grass cover such as turf, because water is captured and allowed
to infiltrate into the soil providing a less hostile environment for soil microorganisms.
Biodegradation of synthetic organic compounds
Turf supports a large, diverse population of soil microorganisms, microflora and microfauna and earthworms. Compared to grassland, the average microbial biomass is 42 per cent less for cropland and 29 per cent less for forests. 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 animal
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 degradation 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 centre 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 attributed to the use of dark surface materials such as asphalt and roofing, reduced vegetation and by the high solar radiation absorbance of urban surfaces or ‘hardscape’ elements of the urban landscape. These three factors contribute to the warming of the air in urban areas, thereby producing a heat island effect. Turf has been described as “nature’s air conditioner” and a type of vegetated surface that can help minimise the harmful human health, economic and environmental impacts associated with the heatisland effect.
Turf grasses reduce 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 nonvegetated 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, researchers 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 temperature of well over 60oC. In another Australian study conducted in the mid-summer with an air temperature recording of 40oC, the surface temperature of turf grass was 45.65oC compared to dark concrete which was recorded at 78.27oC. 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 utilising 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, reflect and refract various unwanted noises. Turf grass also has a far greater success rate of abating harsh sounds than surfaces such as bare ground 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 acts 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’s, 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.
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 the US found turf grass ecosystems can be home to more than 100 taxa including insects, beetles, earthworms, nematodes and other invertebrates.
The Australia turf industry commissioned a comprehensive review of turf’s environmental credentials. The study A Review of the Environmental Benefits of Turf (TU12017) was a levy funded project commissioned through Horticulture Innovation Australia Limited (HIA) and conducted by independent research provider BioScience Australia Pty Ltd. For more information or to download a copy of the full report contact Turf Australia www.turfaustralia.com.au.
Table 1: Summary of the environmental benefits of turf grass.
An independent economic analysis was undertaken and examined two scenarios.
1) A new housing development site and
2) A roadside verge that is 100 metre long and 3m wide.
In both scenarios the cost of a common alternative was compared to that of turf as well as 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 was 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 establishment and maintenance costs during the build were allocated to the turf options.
In Scenario 2, hydro mulch was the most inexpensive option in three of the four possible price combinations, being between 15 and 46 per cent cheaper than turf strips 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 effectiveness of measures in controlling sediment and soil erosion. The effectiveness factor is important and with 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’.