Artificial turf or natural grass, which is better for the environment?
By William Coleman
Artificial turf or natural grass – is one more environmentally favorable than the other? It depends on the factor being considered, such as use of water and chemicals, effects on local climate, and economics among others.
Joe Federico, chief groundskeeper at Tucson High School on Sixth Street at Euclid, provided a tour of the school’s artificial turf field, which he said cost roughly $1 million. At first glance, the field looks impressive.
The deep green base and white borders seem as bright as if they were painted recently, but the field was installed five years ago. The white markers, which identify boundaries for games like football and soccer, are sewn into the field. According to Federico, this “saves the staff time and money by not repainting the field time and again.”
In addition, the lack of paint minimizes chemical runoff, a phenomena in which substances associated with the field are carried away as water runs off. Federico noted that turf doesn’t require additional inputs such as fertilizers and pesticides, which also might be carried off in runoff or leach into groundwater.
When asked about watering requirements, Federico replied, “The only time I water the field is in the summer to cool it down.”
As well as requiring less water, turf requires less maintenance than similar-sized grass fields, he said, mentioning that instead of trimming and cutting, he simply vacuums the field to suck up any loose debris.
Although the initial investment is large, the average life cycle cost over 20 years of use are 15 percent lower than natural grass fields, according to a study by the chemical company BASF, which sells artificial turf.
Federico said he would recommend artificial turf over natural grass any day. Others, however, are less enthusiastic. Although they acknowledge that natural grass uses more water, they point to the cooling value of this use. Unlike artificial turf, natural grass helps cool the air through evapotranspiration, which is evaporation of water from the leafy parts of grass and the underlying ground.
Paul Brown, a professor in the University of Arizona’s Department of Soil, Water and Environmental Science, said “a natural grass field similar in size to an artificial turf field will demand 4 to 5 feet of water per unit-area per year.” Brown also mentioned that natural grass fields require three to four “seedings,” which is the replanting of seeds, per year to accommodate sports activities throughout the season. However, Brown also mentioned a drawback of turf use. He said “turf can cause rug burn,” which are superficial but painful scrapes, on players.
An added downside of turf is that artificial turf may contribute to “urban heat island” effect, in which air temperatures are higher in metropolitan areas than the open country. Higher temperatures are generated by the release of heat, which accumulates during the day in materials of the city, including artificial turf.
Jeffrey Silvertooth, professor and head of the University of Arizona’s Department of Soil, Water and Environmental Science, said artificial turf was “similar to a dark surface on a road.” Like a road or any dark surface, artificial turf will retain and release more heat than natural grass. Natural evaporation and transpiration of water from the grass surface has a cooling effect, like the swamp coolers that are used by people in Tucson. Therefore, dark and non-living surfaces tend to contribute to the urban heat island effect.
Silvertooth provided information pertaining to a 1994 Journal of Environmental Quality paper by James B. Beard and Robert L. Green regarding their study comparing artificial turf to natural turf grass. The study done in College Station, Texas, found dry synthetic sports turf reached temperatures of 158 degrees Fahrenheit, while growing grass which reached temperatures of 88 degrees Fahrenheit during a sunny August day. At night, the synthetic turf was 84 degrees Fahrenheit compared to 75 degrees Fahrenheit for the grass. Their study clearly shows the heat retention capacity of artificial turf is higher than natural growing green grass.
In addition to contributing to the urban heat island effect, artificial turf has a greater potential to increase water runoff than natural grass, due to inadequate filtration from the synthetic turf surface to the underlying ground. This could lead to local flooding.
Also, microbial activity is eradicated in the ground in the application and life span of artificial turf, according to Silvertooth. The disappearance of these beneficial microbes is primarily due to poor aeration, lack of nutrients, and poor filtration, he said. The departure of the microbial community may affect crucial natural process such as nitrification, a process in which atmospheric nitrogen gas is fixed by microbes into a form that can be used for plant nutrition.
In short, there are advantages and disadvantages to using synthetic turf over natural grass in sports fields. Utilizing natural grass requires more labor, water, fertilizer, pesticides, mowing, and paint than artificial turf, which may cause environmental impacts. Drawbacks for selecting synthetic turf include risk of players suffering rug burn, increased runoff capacity that can lead to flooding, loss of local microbial activity, and heat retention that contributes to the urban heat island effect.
In the end, replacing living grass systems with artificial turf may have bigger impacts than anticipated.
William Coleman is an undergraduate in the Department of Soil, Water and Environmental Science with some expertise in Geographic Information Systems.