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NORTH CAROLINA TURFGRASS: Jay McCurdy Ph.D., Associate Professor, Turfgrass Extension Specialist Department of Plant & Soil Sciences Mississippi State University

Recent, rapid urbanization has driven the development of urban green space in the United States and abroad. The world population has almost doubled since 1970, and more than 80% of U.S. citizens reside in urban areas. As a result, much traditionally rural, agricultural, and wild land has been converted to lawns, parks, sports surfaces, etc. for aesthetics, recreation, and ease of maintenance.

Simultaneously, cities and suburbs are filling with folks who are willing and able to change their habits to fit their belief systems—supporting wildlife conservation, reducing inputs like water and fertilizer, and decreasing fossil fuel use. Those trends will continue, so how can the turf industry meet the needs and demands of an increasingly ecologically and socially conscious society?

Turfgrass has a role to play

Lawns and other grasslands are important in built environments. They offer greater noise and heat abatement than pavement, hardscape, and synthetic landscaping. However, turf does not replicate the cooling and shading effects of tree canopy, nor does it fill the habitat void left after clearing and removing natural environments for communities.

Turf provides erosion control, nutrient infiltration, and a familiar, low-maintenance aesthetic. Historically, one of turf’s main benefits has been line-of-sight for protection and separation from other humans and the wild—think roadside visibility, fire abatement, pest control, and home defense. With time, those practicalities have developed into the quintessential “American lawn.” Urban citizens worldwide recognize grasslands maintained as turfgrass lawns or open green spaces, such as parks, for their recreational and social functions as well as their aesthetics.

Problems arise from reliance upon any one system. Turf often lacks species richness, and many modern management practices are ecologically insensitive. For instance, turfgrass’s role in carbon sequestration is often touted, but the positive effect of sequestration may be nullified by management practices such as the seed, sod, and transport to establish, mowing, pest management, irrigation, and fertilization. The literature suggests that even modestly maintained lawns may be net greenhouse gas emitters. Most importantly, lawn-age limits the peak sequestration—that is, once a lawn reaches a certain age (30 to 70 years old), the carbon released through decay equals that absorbed in growth (Gu et al., 2015; Tidåker et al., 2017). Regardless of the net balance, reducing fertilization and mowing frequency are essential to minimizing environmental harms (Law & Patton, 2017).

Repeated pesticide and fertilizer application, as well as mowing, favors monoculture rather than plant biodiversity, although biodiversity is generally a key indicator of healthy ecosystem function. The detriments of “industrial” monoculture lawns have been much-discussed, but few arguments have focused on suitable alternatives for the typical suburban homeowner. Our collaborations with others in the southeast (see RefugeLawn.com)
promise new plant materials and systems that incorporate forbs for pollinator habitat, but changing a societal norm like monoculture turfgrass is a slow process and will not be for everyone.

What does the future hold?

Lawns are not going away, but how we manage them is changing. New approaches to sustainable lawn and land care will incorporate the following principles:

1 ) Plant material selected for low inputs.

Preempting regulation requires good science, and there’s no better science than appropriate species and variety selection. Evaluation efforts like the National Turfgrass Evaluation Program (NTEP), the Turfgrass Water Conservation Alliance (TWCA), and others are trying to guide selection. Considerations include drought and shade tolerance, nitrogen requirements, and required mowing frequency. Progress is also being made to increase lawn diversity by including legumes for nitrogen fixation and nutrient cycling, as well as flowering forbs for pollinator habitat.

2 ) Improved soil–plant interactions.

Broadly, this involves understanding nutrient cycling within living systems and the underlying effects of soil microflora and fauna. These interactions may improve carbon sequestration, reduce fertilizer and irrigation requirements, and substantially reduce inputs in turfgrass systems. We have much to learn but focusing on plant health is undoubtedly our industry’s new direction. The difficult part is educating the average consumer.

3 ) Reduced input.

Lawns are relatively high-input agronomic systems. Nitrogen fertilization, chemical pest management, and mowing require energy expenditure, typically fueled by the burning of hydrocarbon-rich fuels. Equipment and noise emissions from internal combustion engines are key concerns associated with lawn maintenance.

Internal combustion engines power most lawn maintenance equipment, but that is rapidly changing. Stakeholders and operators are adopting electric-powered equipment to conserve fuel, reduce noise, and simplify use. Studies of the cost of electric mowers over a 10-year lifespan, factoring in production costs and fuel emissions, suggest at least a 30% decrease in CO2 emissions by switching to battery-powered mowers (Saidani and Kim, 2021). The emissions are further reduced when renewable energy sources are used to generate electricity.

Many incentives and regulations are guiding the move from gasoline- to electric-powered vehicles, but those initiatives have historically had little effect on the lawn care industry. That trend is changing. For instance, California law (AB1346) will effectively ban gas-powered small off-road engines (SORE) of 25 horsepower or less on January 1, 2024, subject to court injunctions and feasibility studies. The battery-powered outdoor equipment industry is adapting, and not just in California.

Even modern electric-powered mowers are not yet widely capable of performing the functions of internal combustion engine mowers; however, reliable autonomous mowing devices have arisen simultaneously. The installation and maintenance of these devices is a whole new market.

4 ) Lawn for lawn’s sake?

We are witnessing rapid transformation on many fronts. The public perception of landscapes and their roles in society is changing. We are riding a post-pandemic high of outdoor recreation interest, but societal norms, market forces, and regulation inevitably coalesce to challenge entrenched ways of thinking.

For a preview, we must consider regional trends. We see movement toward low-maintenance, live-and-let-live roadsides, parks, and lawns throughout much of Europe. Minneapolis has a program to interseed nitrogen-fixing legumes into lawns. The “No-Mow-May” and “Let-It-Bloom-June” initiatives focus on providing pollinator habitat in England. The U.S. golf industry has done a tremendous job promoting natural areas as beneficial for wildlife (and budgets).

I am both nervous and excited about these challenges. I am not disparaging turf, but I know that turf is only one part of a living, functioning built environment. We need defensible, science-based rationales for why lawns are important and how to improve them. We must also realize that lawn for lawn’s sake is not a winning argument. Our toughest challenge is to make turf both societally and ecologically positive.

References

Gu, C., Crane II, J., Hornberger, G., & Carrico, A. (2015). The effects of household management practices on the global warming potential of urban lawns. Journal of Environmental Management, 151, 233-242.

Law, Q. D., & Patton, A. J. (2017). Biogeochemical cycling of carbon and nitrogen in cool-season turfgrass systems. Urban Forestry & Urban Greening, 26, 158-162.

Saidani, M., & Kim, H. (2021). Quantification of the environmental and economic benefits of the electrification of lawn mowers on the US residential market. The International Journal of Life Cycle Assessment, 26(6), 1267-1284.

Tidåker, P., Wesström, T., & Kätterer, T. (2017). Energy use and greenhouse gas emissions from turf management of two Swedish golf courses. Urban Forestry & Urban Greening, 21, 80-87.