Schools, universities, and municipalities often need to choose between natural grass and artificial turf athletic fields.
Part 1 of this blog series looked at environmental and health concerns associated with artificial turf athletic fields. This blog explores the choice of natural grass for athletic fields.
Research and case studies have identified a range of benefits of natural grass fields for environmental and public health protection, especially when they are managed organically. Case studies find that natural grass fields are cost effective and can fully meet communities’ needs for ample play time.
Organic maintenance practices can improve soil health and eliminate the need for synthetic pesticides or fertilizers. These practices focus on frequent aeration and mowing, as well as soil testing and use of organic fertilizers and soil amendments.
For many communities, the first steps are to diagnose existing problems on a grass field, find guidance, and determine whether the field needs to be rebuilt, or can simply be rehabilitated through improved maintenance.
Soil testing provides information on the physical, chemical, and biological characteristics of soil on a field. Results serve as a stepping-off point to creating a customized maintenance program for individual fields. Using this tailored approach helps avoid overapplication of fertilizers and soil amendments. In addition to finding out about the physical and chemical composition of the soil, communities can use soil testing to assess the health of the community of soil microorganisms.
Rehabilitation vs. Rebuilding
Field rehabilitation focuses on correcting problems, such as water pooling, weeds, or uneven grass cover, by improving the quality of the existing soil and grass. With these steps, many find that their playing fields need no other interventions.
Rebuilding a playing field offers the advantage of designing a field for optimum performance, including optimizing drainage, irrigation, and soil composition.
Taking Action: Best Practices for Organic Maintenance
Maintenance of natural grass can include watering, mowing, fertilizing, replacing sod, and other activities.
Choice of fertilizer is a key component of sustainable natural grass management. Organic (or carbon-based) fertilizer is made with natural, plant- or animal-derived ingredients. For example, fertilizers can be made from soybean meal, feather meal, or animal products. Practices to increase organic matter in the soil will also build soil health and reduce fertilizer needs over time. Use of soil amendments also depends on soil testing, and may include addition of soil conditioner, compost, or lime. Adding compost can also increase diversity of microbes, including fungi and nematodes, which can improve disease resistance.
The term organic fertilizer sometimes refers to any naturally derived, carbon-based fertilizer such as those made from plant or animal products. This does not necessarily mean that a product is certified organic, which provides information about specific standards used in production.
Selecting the appropriate type of grass seed is critical. Individual grass species offer different protective capabilities, such as heat or cold tolerance, drought resistance, deep root systems, and weed resistance. For example, at Denison University (PDF) in Granville, Ohio, the varsity soccer field is planted with bermudagrass and ryegrass. Bermudagrass goes dormant in winter, while ryegrass goes dormant in hot weather. In combination, the two grass types provide a play surface that performs well in a variety of weather conditions.
Aeration relieves compacted soil and dethatches grass to allow air, water, and added nutrients to penetrate the soil. Relieving compaction can improve drainage, decrease the need for irrigation, and create a softer, more protective playing surface. Consultants typically recommend aerating several times per year. The City of Springfield, Massachusetts, for example (PDF), aerates its organically managed fields four times per year.
For more information about organic grass management, see TURI’s fact sheet, “Building an Organic Maintenance Program for Athletic Fields: Guidance from Experts and Experienced Communities” (PDF). The article “How to Avoid Greenwashing and Harmful Pesticides in Lawn Care” may also be of interest.
For those communities that choose artificial turf, maintenance is also necessary. Maintenance of artificial turf systems can include fluffing, redistributing and shock testing infill; periodic disinfection of the materials; seam repairs and infill replacement; and watering to lower temperatures on hot days.
Quality and Playable Hours
Communities often have questions about whether they can fully meet the need for athletic play time using natural grass. Case studies have found that when communities invest in organic management of natural grass, or even just use some of the key best practices of sustainable grass management, they can achieve a substantial increase in playable hours.
TURI has documented the details of playable hours for three communities (VIDEO) in Massachusetts. For example, since starting an organic program for its sports fields, parks areas and other public properties in 2014, the city of Springfield, Massachusetts (PDF) has doubled the number of properties in the program and experienced an increase in overall recreational use due to the improvement in soil and grass conditions. Hours of practice, play and informal activity on Treetop Park, a soccer field, totaled just over 1,000 hours in 2018.
In another example, the Borough of Heidelberg, Pennsylvania chose to improve the athletic field at Heidelberg Park using organic methods. The field is primarily used by children for soccer, football, cricket and softball practices. Poor initial soil quality led to severely compacted soil with poor drainage. The Natural Grass Advisory Group worked with the borough to improve the field using soil testing, aeration, and addition of fertilizer and soil amendments to build soil health and foster the development of a robust root system. After one year, the field had thicker grass cover and a smoother, softer surface.
Flooding of grass fields can be remedied through improved drainage. For example, since Denison University rebuilt its natural grass varsity soccer field (PDF) to address drainage issues, it has had no cancellations due to rain and athletes can play on it even after heavy rain. In fact, it went from being the lowest-performing field, with frequent standing water, to a high-performing field that visiting teams often request to play on.
Organic turf maintenance can be cost-competitive with conventional management. One study found that once established, an organic turf management program can cost 25% less (PDF) than a conventional turf management program. In TURI’s 2019 case study, Springfield, Massachusetts officials estimated that the annual total for products, maintenance and labor for organic grass maintenance was just under $1,500 per acre.
Denison University’s cost for 21 acres of natural grass field maintenance is just under $1,800 per acre, not including costs of pesticides. Its staff state that the cost of products for natural grass management is falling as interest and demand in this area grow. The grounds manager has found that the grass fields are far more cost effective than the university’s one artificial turf field once the full costs are factored in. Denison resurfaces its artificial turf field every seven to eight years, at a cost of about $800,000, and spends about $115,000 annually for maintenance.
More detail about playable hours, maintenance, costs and more can be found in the case studies and other resources listed below.
Environmental and Health Benefits
Organically or sustainably managed natural grass fields offer a variety of benefits.
Natural grass athletic fields may require irrigation at times. However, following organic management practices reduces water needs by supporting root development. Using a “smart” irrigation system, as described in the Martha’s Vineyard case study (PDF), can maximize benefits while conserving water.
Well-designed and maintained grass fields absorb rain. Some schools and communities interested in environmental sustainability pair grass athletic fields or other green spaces with stormwater management features like rain gardens, and include educational signage about their benefits.
Conventionally-managed natural grass may be treated with synthetic pesticides or fertilizers. Some commonly used pesticides are linked with serious health impacts, including asthma, Parkinson’s disease, fertility-related problems, and cancer.
Organically managed natural grass builds soil health, making it unnecessary to apply chemical treatments. Organic fertilizer is better absorbed than synthetic fertilizer, which means less runoff that can contribute to algae blooms.
Grassy areas help to reduce the urban heat island effect. Natural grass athletic fields do not heat up the way artificial turf fields do. The school board of Burlington, MA adopted a policy that delineates heat and humidity conditions under which athletes may not use artificial turf fields and must move to grass fields to protect them from heat-related health concerns. And scientists are investigating soil as a potential carbon “sink” that can contribute to carbon sequestration, pointing to an additional possible benefit of grass.
Grass fields, especially managed organically, may align with policies or programs such as climate change action plans or green certification programs like the Sustainable Sites Initiative. Natural grass also provides habitat for a range of organisms; organic practices protect pollinators.
About The Authors
Susan Kaplan is an environmental health lawyer and a professor at the University of Illinois Chicago School of Public Health. She contributes to projects at the Toxics Use Reduction Institute on a consulting basis.
Lindsey Pollard is Special Projects Research Associate at the Toxics Use Reduction Institute at the University of Massachusetts Lowell. Her work includes policy research, researching chemical hazards associated with consumer materials, finding safer alternatives and sharing findings with communities.
Dr. Rachel Massey is Senior Associate Director and Policy Analyst at the Toxics Use Reduction Institute at the University of Massachusetts Lowell. Her work includes policy analysis at the state, federal and international levels, as well as work with communities to reduce toxics at the local level.