The benefits of growing grass
Turfgrass offers many environmental benefits that have been identified and studied over the last 50 years (Table 1). The environmental benefits of turfgrass are not promoted as much as they should be, and in many cases turf gets blamed for such things as nutrient leaching and overuse of chemicals when science has proven that not to be the case. Nevertheless, each facility should strive to minimize its carbon footprint, particularly when it comes to inputs like mowing, fertilizer applications and irrigation. Water conservation is especially important, not only in arid regions of the U.S., but also in the urban environment. Water usage in the U.S. breaks down as follows: 43 percent used by industry, 47 percent use by agriculture, and the remaining 10 percent used by households (bathing, cooking, sanitation, drinking) and landscape irrigation. One comment we might hear is that golf courses and homeowners are water hogs, but in fact only 9 percent of golf courses use public water (the rest is supplied by wells and other on-site sources) and most homeowners in the U.S. don’t apply any water or fertilizer to their lawn. Approaches to minimizing irrigation include using bermudagrass (low water use rate) or tall fescue (drought tolerance), or allowing certain grasses to go dormant during the summer if fields are not in use, as well as auditing the irrigation system and apply water to fields (natural and synthetic) through best management practices (BMPs).
Technological advances in the industry have allowed field managers to grow turf year-round, even in shade. Pictured is the Galatasaray soccer stadium in Istanbul, Turkey.
PHOTO BY PHIL SHARPLES, FIELD MANAGER.
Turfgrasses for sport and recreation
In addition to environmental benefits, turfgrass is used extensively for recreation and sport. With over 34,000 acres of athletic field turf and more than 700 golf courses in Ohio alone, sports are important not just to the economy, but also to people’s health and well-being. Per the U.S. census, there are 267 million people in the U.S. age seven and older. Of those 267 million people, around 80 million people (30 percent of the population) play sports outside. Within the top five sports, it is estimated that golf courses have the most activity at 25.6 million, and baseball and soccer have around 15 million regular participants (Table 2). The importance of encouraging people to play sports and offering them places to play those sports cannot be downplayed, particularly when the Centers for Disease Control and Prevention estimates that 17 percent of American children and adolescents are obese.
Natural grass has been and continues to be the standard benchmark for a good quality and safe playing surface. When evaluating the quality of a playing surface, the surface hardness (impact absorption), traction and ball response is determined by using industry standard equipment that is recognized by organizations such as FIFA, the ASTM and the STRI. Those parameters were originally determined by measuring high-quality natural grass fields and coming up with preferred and acceptable ranges based on player surveys and epidemiological data. The FIFA Quality Concept and other sports governing bodies’ recommendations are therefore based on natural grass fields.
One unique benefit to a natural grass playing surface is its ability to divot, or “give,” under foot traction. During sports with intense athlete-surface interaction, like sliding tackles during soccer, cutting maneuvers in football or scrimmages in rugby, it is important that the foot does not become stuck in the surface, potentially causing lower limb injuries like ruptured ACLs. Cool-season grasses typically have rotational traction (peak torque) values around 60 N.m if the athlete is wearing a standard .5-inch cleat. Bermudagrass peak torque is typically around 75 N.m. Hybrid systems (natural grass seeded into a synthetic base) have greater traction values if the synthetic fiber comes into contact with the athlete’s shoe (in our research, peak torque was 90 to 114 N.m at .75-inch cleat depth and exceeded 160 N.m. once the cleat extended into the synthetic base at 1.25-inch depth). Synthetic turf research at Michigan State University (MSU) reported peak torques in the range of 78 to 135 N.m, depending upon shoe type. Clearly, the length of the cleat has a significant bearing on traction values. Unfortunately, there is currently no recommended upper limit for peak torque, since natural grass was used as the benchmark and that rarely exceeds 70 N.m. What becomes the accepted standard in the U.S. is something that turfgrass research programs are working on.
Turfgrass usage and longevity
A common question pertaining to grass sports fields is “how many games can a field host,” but there is no one easy answer, since each field is unique in its construction type, its location and, most importantly, its level of care. For the sake of the article we can assume that a native soil field should be able to host 25 to 100 sporting events a year if it gets a certain level of management and there are very few rain games. Soil fields that are topdressed with sand or sand-slit and receive a higher level of care are at the top of that range. Soil fields receiving little or no care are at the bottom of that range. Sand-based fields can handle more events.
Table 1: Environmental Benefits of Turfgrasses
Adapted from Beard & Green (1994) and Sherratt et al (2011)
The cost of building and maintaining sports fields
The cost to build a high-quality sand-based field and maintain it properly over a 10-year period is dependent on many factors. New fields require a large outlay of approximately $500,000 to $1 million at the beginning, and then annual maintenance like painting, irrigation, grooming, topdressing, etc., which adds up to between $30,000 to $50,000 per year. A general guideline would be a total of $1.5 million over a 10-year period. Obviously, it’s less expensive to maintain a native soil, amended soil (sand slits/sand cap, etc.) or existing sand-based field over the same 10-year period. Those costs will be in the range of $50,000 to $500,000 over the 10 years. The decision to build a new field or to renovate and maintain an existing field should be made after careful consideration of the following questions:
Is there a qualified sports turf manager on site? A sports field manager is the key to successful fields and should be the number one budget priority for any sports facility. A sports field manager will keep fields safe and playable whether they are natural grass or synthetic turf. In many cases high schools choose to install a synthetic field based on the fact that they do not have a sports field professional to take care of natural grass, and they assume synthetic is an easier, maintenance-free option. It makes more sense in the long-term to hire a professional to take care of all fields and grounds.
Table 2: Participation in SelectedSports Activities
Ref: Table 1248. Participation in selected sports activities:2008. 768 Arts, Recreation, and Travel. US CensusBureau, Statistical Abstract of the United States: 2011
How many events per year will the field host? If the answer to that question is less than 100 events per year, then it might not make financial sense to build a new sand-based or synthetic field. Amending the existing native soil field with sand slits or an amended rootzone makes more financial sense. If, however, the field is used excessively and there are issues with cancelled games due to inclement weather or overbooking, then synthetic turf may be the answer.
How many fields are there? Can games be scheduled on different fields allowing some fields to be renovated? Is the site landlocked with just a few fields servicing a lot of people? Again, intense use with few fields to accommodate the community would be a scenario for synthetic turf. However, if there is space for other fields or practice areas, then a sports field manager could help to get those fields developed and usable.
Table 3: Examples of Events onNatural Grass Fields*
*Via correspondence with sports field managers
**Includes all events: games, practice sessions,camps, concerts and corporate
***2 hours/day x 6 days/week x 40 weeks duringseason (480) + 4 hours/day x 7 days/week x 4 weekspreseason (112)
In summary, natural grass sports fields offer environmental benefits to the community and they are low-cost. If they are maintained by a sports field professional, natural grass fields can produce a playing surface second to none, and as we see in Table 3, they can clearly host a large amount of events. As an industry we really need to tout the benefits of trained sports field professionals as much as possible, because the sports fields that are built are only as good as the person that takes care of them. It’s rather sad to see a high school put so much money into a new grass field only to have it destroyed after a few games because no one knows how to take care of it. Given the opportunity, a professional sports field manager can produce the best playing surface in the world with natural grass.
Pam Sherratt is a sports turf specialist at Ohio State University and served on the STMA board of directors from 2010-2011.Dr. John Street has been a professor in turfgrass science at Ohio State University for the last 30 years.