Carbon smart sportsfields

We hear a lot about sustainable golf course management in the turfcare industry, but the topic of sustainability is not widely discussed within sportsfield management circles Here, Megan Hood, former STRI Agronomist and now working 'back home' for the New Zealand Sports Turf Institute, suggests that improvements can be made.

With increasing pressure on local and national governments to be more environmentally responsible, sportsfield managers are investigating ways to improve the sustainability of their facilities. This article aims to introduce areas where improvements in the environmental sustainability of sportsfield and amenity turf areas can be made.

Topics to consider include:

• Fuel use/mowing requirements
• Use of recycled materials/green waste
• Pesticide use
• Minimising water use
• Reducing 'product miles'
• Waste disposal

Fuel use/mowing requirements

Fuel use is one of the primary sources of carbon emissions from the sportsfield industry. Mowing can also account for at least 60 percent of the maintenance cost of some sportsfields. Minimising fuel emissions and costs is a high priority for many councils. Factors to consider include:

• Mowing frequency
• Machinery selection
• Machinery maintenance
• Select slower-growing species to reduce mowing frequency
• Create managed grassland in amenity areas
• Use of growth regulator where appropriate (e.g. Primo Maxx)
• Reduce fertiliser applications to minimise mowing requirement

Mowing frequency

Mowing regimes can be specified either in terms of a fixed time interval or grass length. Mowing frequency needs to be closely related to growth patterns. Fixed interval mowing is easy to apply and plan for. It is often the better arrangement for high quality, close-mown turf (e.g. cut at fixed frequencies of say two or three times a week). The problem with managing sportsturf areas in this manner is that we often mow when the grass doesn't need it.

Grass length mowing defines when to mow by the height to which grass is allowed to grow before it is cut, with the interval between cuts varying according to rate of growth. This method is much more likely to reduce carbon emissions, however it makes planning of works more difficult.

Machinery selection

Careful machinery selection can significantly reduce the fuel required to mow a set area. Electric mowers are becoming more common worldwide (mainly coming from the golf industry) and are likely to become more common in the UK. The introduction of the much-improved large electric zero-turn mowers to the US market in 2006 has resulted in a rapid uptake of the technology there. The batteries of the new units will last for fours hours (continuous use) with one charge.

Petrol and diesel engines are commonly available on ride-on mowers. Liquid-cooled, diesel engines tend to be longer-lived and require less maintenance than a standard air-cooled petrol engine. Diesel engines are also more fuel-efficient than 2 or 4-stroke petrol engines, although they do produce greater quantities of sulphur dioxide, nitrogen dioxide and particulates.

Liquid petroleum gas (LPG), a by-product of North-sea oil production, is one of the fastest growing commercial fuels in the UK. Its use within an engine gives no discernable difference in performance to traditional fuels and emits up to 99.8 percent less pollutants. Converting engines to LPG is becoming increasingly popular and is likely to become more common in the turf industry.

Wide area mowers (WAMs) can also reduce fuel emissions when mowing large, open areas such as sportsfields. When selecting a mower for an amenity area, consider the size and shape of the areas to be mown. Assess the spacing of trees, buildings, fences and other site features that will impact the mowing operations.

Using a WAM or large deck mower will not always mean the job gets done faster or more efficiently. Newer, smaller mowers may actually produce a better-quality cut at a faster speed, making the entire job less time-consuming and fuel-efficient. Smaller mowers can be more versatile and easier to use around landscaping and trees, as well being easier to transport.

Tyre size is also an important factor with regard to energy use. A recent study indicates that the use of large tyres on tractors compared to small tyres can reduce fuel use by up to 10 percent.

Machinery maintenance

If the machinery that you are using is getting old, the chances are it is not as energy-efficient as the new technology. In some cases, newer machines can reduce ground-level emissions by 70 percent.

It is important to keep machinery well maintained and regularly serviced. Most turf managers are aware that it is important to keep mower blades sharp in order to achieve a good quality of cut, however, it is also important to note that a properly sharpened and balanced mower blade will also reduce mower vibration, lengthen mower life, and reduce fuel consumption by as much as 22 percent.

Monitoring fuel use is an important tool in assessing the fuel-efficiency of both your machinery and management systems and should be recorded and assessed annually.

Grass selection

Many council-owned facilities were originally sown with agricultural cultivars which were designed for maximum grass production. When sowing new facilities, councils should consider slower-growing options such as dwarf type perennial ryegrass, fine fescues and browntop bentgrasses. The most appropriate grass species and cultivars can be determined from Turfgrass Seed, published by BSPB and STRI.

Creation of managed grassland

Urban parklands have been mown wall-to-wall for many years. However, many councils are now installing managed grasslands in urban parks to improve ecological diversity and to reduce mowing requirements. This may also involve the deliberate introduction of wildflower species to the grassland and, in some cases, may require 'defertilisation' of the underlying soil in order to reduce the growth rate of the grasses so that the wildflower species can compete. It is also important to keep the park or sportsfield user informed; otherwise it might be thought that the grass has been left uncut through accidental omission.

Growth regulators

Plant growth regulators can be a useful tool in reducing carbon emissions, with regular applications of the turf-registered Primo Maxx reducing mowing requirements by up to 30 percent. However, it has to be recognised that energy is required to produce and apply the growth regulator.

Synthetic fertiliser inputs

Reducing fertiliser inputs has a double benefit in that it reduces mowing requirements and reduces the energy needed to produce the fertiliser. Creating synthetic nitrogen for fertilisers requires the heating of natural gas to combine atmospheric nitrogen and hydrogen into ammonia. The amount of natural gas required to make approximately 200 bags of lawn fertiliser would heat an average home for a year. Transporting these bags of fertiliser from the factory and to the turf facility also requires additional fuel.

Over-fertilisation is a common problem in the turf industry and many councils are now reviewing their fertiliser inputs (and types). Often, all turf areas are treated the same, regardless of soil type, grass type, turf quality and expected wear. Take advice on matching fertiliser inputs with these factors in mind rather than using a prescribed 'programme'. In some cases, major reductions in fertiliser inputs have been achieved without a reduction in the quality of turf provided.

Assess each turf area to see if the fertiliser volume and type is appropriate. Sportfields and amenity areas are frequently fertilised with one or two large applications per year. Switching to slow-release or organic products can significantly improve the efficiency of fertiliser applications and reduce overall emissions.

Use of recycled materials/green waste

The use of recycled materials and green waste is increasingly popular in turf management.
Materials available include:

• Recycled glass topdressing material
• Recycled compost/green waste products
• Topdressing material with recycled compost rather than excavated soil for organic component

Recycled glass topdressing material

The STRI is conducting two sets of trials assessing the use of processed sand on artificial and winter sports pitches funded by WRAP (the Waste & Resources Action Programme). In the first trial, processed sand manufactured from 100 percent recycled glass will be tested as a material for the construction and maintenance of second and third generation artificial sports surfaces.

The second trial will assess the performance of processed sand as a topdressing for natural football pitches. The STRI has linked up with Tameside Metropolitan Borough Council to carry out the trial on four of its football pitches. As part of the trial, the pitches' playing and turf quality will be monitored and pitch users will be asked their opinions on the use of processed sand to see if playability is improved.

Green waste

There is widespread use of green waste products in the golf industry (mainly as an additive to topdressing material as a replacement for peat) and the use of green waste materials is also increasing in the sportsfield industry. Green waste is being used for both topdressing and as a soil amendment in new constructions. One of the main reasons for the greater confidence in the use of compost is the improving standard and quality of the materials available.

A recent study indicates that topdressing sportsfields with green waste applications (ideally at a rate of 4 litres/m2) can improve turf quality in the long-term whilst reducing the amount of green waste going into landfill. There is an immediate release of organic nitrogen to the turf after compost application, but the main nitrogen component is of a slow release nature, which is generally considered to be released over a two-year period.

Further information on the use of compost on sportsfields is available on the publications section of the WRAP website www.wrap.org.uk.
Pesticide use

Integrated pest and disease management is the way forward, using chemical and cultural techniques to complement each other until a more disease-tolerant grass equilibrium can be reached. If problems escalate to a point where a pesticide application is required, select the lowest toxicity product available and only apply to affected areas (i.e. spot treat as necessary).

Minimising water use

Minimising the use of fresh water for irrigation is becoming a higher priority for UK turf managers (especially those in the South East of England) and many are finding that irrigating with fresh water is no longer an option. Good practices include:

• Select grasses with low water use rates
• Use of finer grasses on low-wear areas and amenity lawns
• Ensure that irrigation systems are efficient where used
• Use aeration, wetting agents and hand watering where possible to make best use of the water you have available

Many countries utilise grey water/recycled water to irrigate where necessary and this may become an option in the long-term.

It should also be noted that topdressing with green waste compost (see above) improves the water holding capacity of the rootzone and enhances turf growth under hot, dry weather conditions.

Reducing 'product miles'

The 'buy local' campaigns that are prominent in the food industry do have relevance to the turf industry. Buying locally produced goods can significantly reduce the energy required to get the products to the end user. Many fertilisers, amendments and machinery options are produced in the UK and it makes sense to source local goods where possible.

Waste disposal

Waste disposal is a major issue in the turf industry and turf managers need to ensure that they consider waste management options. A waste management audit will immediately flag up opportunities for waste minimisation and cost reduction, and these will form the basis of a long-term waste minimisation strategy (Penrose & Taylor 2007). An audit should include the following:

• Clippings disposal
• Wash-down bays/recycling systems
• Machinery disposal
• Pesticide management
• Oil disposal

For further information on waste management audits visit www.stri.co.uk.

Conclusion

The cumulative effect of many small management changes can have a significant effect on the overall environmental impact of turf management activities. Many of these changes have zero financial cost, but can create significant environmental benefits. It is also worth remembering that the turfgrass sward itself is locking up carbon within the soil/root system and can provide a contribution to the reduction of atmospheric carbon dioxide levels.

Megan Hood www.nzsti.org.nz/about-nzsti.html