Is grass always greener? Evaluating environmental impact of synthetic sports pitches

Should we pass on plastic pitches? With conversations kicking off about plastic in sport, water use on turf and year-round pitch performance, how do you find the perfect pitch? 

At Fidra we want to see communities playing on pitches with the lowest possible environmental impacts, whatever the pitch is made of Though it’s often seen as a debate of grass vs artificial” in reality picking a pitch is a game with more than two players. Communities face tough choices when investing in outdoor pitches and finding suitable sport sites. The perfect pitch for one site may not work for another and it all depends on where the pitch is placed is and how it is going to be used.   

The Roots of the Debate

The debate between a plastic and natural pitch has been ongoing since Monsanto put ChemGrass (later renamed AstroTurf), on the market in the 1960s. Grass has always been tough to beat when it comes to playability and the hard, rough surfaces of early synthetic models were unpopular for causing injury. The ‘third-generation’ (3G) pitch now developed for contact sports like rugby and football has boosted artificial pitch popularity. By 2020, it’s predicted that there will be 21,000 full-size, and 70,000 mini artificial pitches installed across Europe, almost double the pitches we had in 2012. 

A poor quality artificial pitch disintegrating at the end of its usable life.

Plastic for performance 

3G technology creates a safer and more realistic playing surface than previous synthetic turf pitches by including a layer of loose elastic performance infill, usually a granular rubber crumb from ground-up road tyres (i.e. microplastic), to act as artificial soil between synthetic grass blades.  

This synthetic rubber is a microplastic and can leak from the edges of the pitch, get trodden off by players, and wash down changing room drains, ending up as a surprisingly significant source of pollution to the environment. With the dramatic rise artificial pitches, total plastic emissions are expected to double by 2035. This was our route into investigating artificial pitches, and we’ve been promoting practical solutions to this problem together with our partner organisation KIMO International via our Pitch In project. Check out our guidelines here. 

To assess the full environmental impact of any pitch, you need to look at its whole life cycle, from production to disposal. Microplastics are just one of many facets that need to be considered…

A pitch for sports or walks and worms?

A big advantage of a synthetic surface is simply that it can be used for sport far more regularly, and over more seasons, than a grass one. While grass needs time to recover, artificial pitches can be used by one sports team after the other, providing more training time However, grass pitches are also often used by communities for other activities not just training and matches. 

Cost will always be a factor in the choices we make. A grass pitch is much cheaper to install coming in at up to £100,000 per pitch compared to the £400,000-800,000 you must pay for your average artificial install. On the other hand, an artificial surface provides increased revenue for pitch owners, giving a speedier return on their (albeit initially larger) investment. Where rain and snow often cause games to be cancelled on real grass, an artificial pitch can be used in almost all weathers and seasons – across the year this can mean a tenfold difference in player hours on an artificial pitch compared to natural grass in Scotland. In a society where access to outdoor play and obesity remain a problem, this practical advantage is not to be sniffed at. Either way, are the hours of play the only aspect to consider when choosing between grass and synthetic fields? 

Lets not forget, real grass playing fields contribute to valuable green space in urban communities, providing immeasurable well-being benefits. For recreational purposes it’s the most versatile of all sports surfaces; providing room for picnics, play and community eventsGrass stains on shorts, mud caked knees, the smell of freshly cut grass or the feeling of grass between your toes; these are things that make a playing field more than just a football pitch – it provides a place to connect with nature, which shouldn’t be underestimated as we strive to protect our dwindling green spacesKeeping our last bastions of soil is also vital for our threatened biodiversity – a lawn can be an important home to microbes, insects and wormsHowever, if you’re keeping it to professional standards, a well-manicured grass pitch can barely be termed a ‘natural’ surface, with maintenance aiming to keep nature out.   

Sun and rain 

A poorly drained grass field can lead to reduced training time (Photo credit: Mike Pennington)

In dry climates, use of 3G artificial pitches can clearly save water – US research showed that each fullsized rectangular football field saves between 1.8 million and 3.7 million litres of water each year compared to its natural equivalent. This argument is less likely to hold true in Scotland with ample rainfall to keep grass pitches watered, while professional hockey pitches, that are always artificial, are intensely watered to optimise ball performance. Grass fields can also provide much-needed drainage in an increasingly impermeable environment, though on a poorly drained pitch, games can often be flooded out or turn into a mud bath in rainy weather. 

 

While artificial pitches can get uncomfortably hot in sunny weather, natural grass keeps its cool, absorbing the sun’s rays and transferring that energy to growing plantsSynthetic pitches can reach temperatures of 70°C on a hot day, up to 40% hotter than a natural field. This is not only uncomfortable for players but can also contribute to the urban heat island effect, increasing local air temperature by up to 4°C.  

Carbon counting 

Carbon footprints of artificial and natural pitches have been compared in a few studies with different results (e.g. 1, 2), but it’s clear that a plastic pitch, made from fossil fuel-derived materialsis more carbon intensive in its production. Both pitch-types use energy for installation. A grass pitch has more energy-intensive maintenance requirements, namely fertilizing and mowing, but this varies depending on the methods used and quality of the pitch required (e.g. professional or community use)If well-managed, a grass surface might act as a net carbon sink. The same cannot be said for synthetic surfaceswhile you might think synthetic pitches are ‘maintenancefree’, industry are often quick to clarify that regular upkeep is important to extend its lifespanArtificial pitch maintenance equipment also uses energy, and there is no carbon sink to make up for it 

End of life  

grass pitch is a self-renewing, growing surface. If well-maintained, a grass pitch is theoretically self-renewing. Even if a surface is replaced (every 10-20 years to maintain a professional pitch), the waste is still biodegradable. Synthetic pitches on the other hand have a serious problem at end of their 8-10-year life span. Most current pitch ‘recycling’ services generally re-sell the plastic carpet in small patches for landscaping, or as a base for horse stables. These old plastic carpets don’t go away but are likely to crumble in situ, contributing to the microplastic problem, and excess old pitches have led to stockpiling problems.

Pitch recycling services will often cut up pitches and sell on for landscaping, but this can lead to stockpiling – image www.softsurfaces.co.uk

In defense of the plastic pitch some would argue that they are actively diverting waste from landfill, with the equivalent to 12,200 tyres being repurposed into SBR infill for each fullsized artificial turf fieldRecycling technology is also being developed that has the potential to recycle 99% of pitch materials. There is therefore ongoing scope to incorporate artificial pitches effectively into a circular economy, while technological developments are also helping grass sports pitches to be fit for the 21st century, becoming more durable with less need for fertilizers and pesticides.

 

Chemical leaching 

Not only microplastic escapes from a synthetic pitch. ‘Plastic’ is a chemical cocktail, and contaminants and additives within performance infill can leach out. The styrene-butadiene-rubber (SBR) granules made from ground-up tyres have been investigated due to potential concerns for human health from exposure to harmful substances such as polyaromatic hydrocarbons (PAHs). Although current studies show that levels of exposure are unlikely to be a risk to humans, leaching of heavy metals such as zinc from SBR pitches can occur at levels that harm local ecosystems.  

Though our souls might yearn for an organic, mulchy sod, grass lawns also have chemical implicationsWhen grass pitches are maintained using fertilizer and pesticides this leads to contaminated run-off that is also potentially harmful to the environment, and though some herbicides and fungicides are still needed for artificial surfaces, they are in lower quantities than if you’re trying to keep a manicured lawn. 

For both types of pitch, design, treatment choices and effective management can significantly clean-up chemical run-off and its impact on the environment.  

The final score 

So which grass is greener? It’s clearly not black and white. How green a pitch is depends not only on whether it is artificial or grass, but also on its component parts, the context of its climate, whether it’s designed for professional use or for communities. A well-managed artificial pitch may be an appropriate choice where the alternative is a fertilized, water intensive, pesticide-heavy professional pitch. On the other hand, a poorly maintained 3G pitch is not only a poor environmental choice, but also a poor playing surface.  It’s about choosing the right pitch for the right location and use. An artificial pitch can be a useful training surface and an opportunity for more exercise, but it shouldn’t be seen as a replacement to connecting with nature.  

For both natural and artificial pitches, we can use correct management and technological developments to reduce environmental impact, if people create enough demand for it

That’s why we’ve taken a pragmatic stance on the issue of microplastics on pitches. We’re working together with industry, sports associations and decision makers to spread the word about best practice in design, maintenance and use of artificial pitches, to reduce the spread of microplastic.  

Why not join the Pitch In team to find out more?
www.team-pitch.in   

 

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