(Comment: This is adapted from a 25 Sep 2013 letter that I wrote to the Mayor and Commissioners for a friend concerned about her city’s plans to replace natural turfgrass fields with synthetic. I have since been engaged in consulting projects that involved the choice between natural and synthetic fields, which did not change my outlook since 2013. In full disclosure, I am an expert on natural turfgrass and not synthetic, and my esthetic preferences are for natural. But I see that each has its place. There are only two cited references here, but a search of key words will result in more updated references to these same topics.)
South Florida communities are occasionally confronted with the choice between natural turfgrass playing surfaces and synthetic. In the decision process, one can be distracted by headline risks of synthetic, such as bodily injuries, flesh-eating bacteria, lung damage from infills, and burns from high temperature plastic, versus natural, which has risks of injuries, pesticide exposure, and costs of irrigation and fertilizer.
Background
Not to ignore the headlines, real-world decision makers must consider dull subjects such as amortized costs, the use requirements of different athletic clubs which duel for scheduled hours, rainout frequency, carrying capacity, and landscape esthetics.
Real world issues, such as painting lines for different sports and the problem of leaf litter in synthetic fields, sometimes tip the balance to natural. The whims of major sports leagues swing the balance at the local level from natural to synthetic, and back again. The agronomic failure of cities and schools to properly maintain natural fields, the unsuitability of equipment, and ignorance of soil physics and particle sizes, may tip the balance to synthetic.
There is also aggressive, effective sales promotion of synthetic fields, and easy financing through grants, which make a side-by-side comparison difficult. Natural turf fields are also vulnerable to snake-oil sales people who reduce the credibility of Certified Sports Field Managers and leave decision makers confused.
There has been steady improvement in synthetic fabrics and infill materials, so experience must be updated to present better potential of new synthetic materials. Both natural turfgrass and synthetic fields provide advantages and disadvantages, with different financial and capacity consequences.
Examples
Some venues such as the high-intensity, 220-acre ESPN / Wide World of Sports complex, are constructed with natural turf. Another venue, the City of Lauderhill Sports Park, has a synthetic soccer field complementing other natural turf facilities in the region. Different entities may reasonably come to different decisions that are each economically justifiable under different circumstances. In these two cases, neither field complex chose an “all eggs in one basket” approach. That sense of balance is shown also in the comments of sports turf managers who maintain both natural and synthetic fields (see Tarantino quote at the end of this letter).
Cost
A sound financial comparison must not underestimate the maintenance costs of synthetic fields, for additional infill, detritus removal, chemical disinfectants, and erasing temporary lines, as well as the expected grooming, repair, and irrigation to reduce heat, and, believe-it-or not, weed control. Synthetic is not maintenance free.
Maintenance costs for natural turfgrass are much higher than synthetic fields. Unlike synthetic fields, natural turfgrass has costs for fertilizer, irrigation, mowing, pesticides, core cultivation (aerification), and possibly overseeding.
Both kinds of surfaces require considerable capital investment for equipment and installation. The capital investment for synthetic field installation is much greater than for natural turf. Reports have indicated that the longevity of a synthetic field may be 8 to 10 years, or 6 to 12 years, after which the field is replaced and the old field disposed of or recycled by the manufacturer. So initial investment and continuing environmental costs of pesticides and fertilizer (natural turfgrass) should be compared with the investment and environmental cost of disposal (synthetic fields).
Careful consideration of operating expenses and the opportunity cost of capital, along with the greater use capacity of synthetic fields (considering weather), can predict an optimum choice of either synthetic or natural turfgrass sports fields, depending on the assumptions and conditions.
Climate and use
Synthetic surfaces may be an optimum choice in temperate climates where limited months of growing season occur, in indoor stadia where there is limited light, and in situations where there is heavier play demand or need for more dependable play, or multiple sports.
Natural turf may be an optimum choice in warm climate where the growing season is long, in outdoor stadia, in situations where there is lighter or variable play, and where there are esthetic landscape interests. But there are limits.
In a 2004 circular, Dr. Grady Miller (Miller, G. L. 2004. Athletic field capacity. ENH 991, University of Florida. 3 p.), estimated the effects of hours use for football and soccer fields from a survey of turf managers and municipality supervisors. Miller stated that sustained field conditions were:
- “good” – 200 hours field use per year
- “fair to poor with some thinning and localized wear” – 400 to 600 hours per year, and
- “significant turf loss, field surface damage, and increased potential for athlete injury” – over 800 hours field use per year.
Irrigated natural turfgrass evaporates and transpires water into the atmosphere, which provides a substantial cooling effect, and non-irrigated synthetic fields do not. The surface temperature of non-irrigated synthetic fields was reported in multiple studies to be several tens of degrees Fahrenheit hotter than irrigated natural turf. A difference in temperature is also observed in the ambient air where athletes perform. Increased heat from synthetic fields can affect athlete performance and health, particularly in warm climates.
It is correct that synthetic fields do not grow and do not require irrigation for evapotranspiration, but they are sometimes irrigated to lessen temperature. Any water savings for not irrigating must be counterbalanced with the cost of player overheating.
Health and safety
Also on health and safety, recent studies have tended to show similar risks, in incidence and/or severity, of injuries from natural turfgrass and synthetic surfaces, however, there are reported differences in the types of injuries. Two reports indicated a higher risk of ankle injuries on synthetic fields. A problem described in these studies has been inconsistency in conditions of natural turf which makes comparison difficult. Also there have been differences historically as synthetic surfaces have gone through several generations of improvement, as stated above, so earlier injury comparisons are not representative of today’s products.
In synthetic fields there are reported health concerns over volatile organic compounds, benzothiazole, nitrosamines, particulate matter, and other crumb rubber-related materials, particularly for indoor settings. In natural turfgrass there are health concerns over pesticides which are applied intentionally and are regulated by the EPA.
In synthetic fields there are reported concerns over the possibility of infection by methicillin-resistant Streptocaucus aureus (MRSA), particularly in indoor sports venues where the bacterium can live for a few hours or days but is still believed to be more often transmitted between people and has been shown to have poor survival on synthetic fields outdoors.
Realizing that there is a lot of information that goes into your decision, I hope you can prioritize what is known, and on what authority or confidence level, and what is important for the residents and neighbors. Besides considering the financial and other consequences of your decision, please consult with sports field managers and others who have familiarity with both natural and synthetic fields.
Practical experience
Michael Tarantino, CSFM, Director of Facilities, Maintenance and Operations, Poway Unified School District, said (excerpt from Sports Field Management Magazine by 2013; see also comments in Forbes on “Buyers remorse surfacing over artificial fields https://www.forbes.com/sites/mikeozanian/2014/10/22/buyers-remorse-surfacing-over-artificial-turf-fields/),
“I currently maintain approximately 19 acres of synthetic turf and 158 acres of natural grass including warm and cool-season turf at the Poway Unified School District.”
“There are pros and cons to both synthetic and natural turf. While the natural turf on the high-profile fields requires heavy maintenance (approximately $40,000 per year per 2-acre parcel), the synthetic maintenance cost is running approximately $7,000 to $8,000 per year per 2-acre parcel, regardless of the application. The real pro and cons of this subject are overuse on natural turf versus replacement cost of the synthetic fields. Many entities using synthetic are not thinking about the replacement cost, however, if you have an overused (multiple sports running in parallel) high-profile field, synthetics may be your answer. But don’t forget the replacement costs.”