Lawn Carbon Sequestration Report: What the Science Says

Contributors: Dr. Kelly Kopp, Alec Kowalweski, Ph.D.

Introduction

Agencies and utilities frequently promote replacing lawns with xeric landscapes, artificial turf, or gravel, often framing turfgrass removal as the most straightforward solution for reducing outdoor water use. These efforts have promoted turf removal as a water-saving strategy, but they overlook the important role turfgrass systems play in maintaining soil carbon storage and supporting urban carbon sequestration.

Managed turfgrass systems represent one of the most widespread opportunities for soil carbon sequestration in developed environments. Dense fibrous root systems and continuous belowground carbon inputs allow the soils beneath turfgrass to accumulate and retain significant amounts of soil organic carbon over time. When turfgrass is removed, these stable soil carbon pools can be disrupted or lost altogether, particularly when soils are disturbed or replaced with impervious or biologically inactive surfaces.

Although reducing water use remains an important objective, it is not necessarily achieved by turfgrass removal. Further, removing turfgrass can unintentionally reduce the carbon sequestration capacity of urban landscapes and contribute to greater climate vulnerability. A more nuanced, evidence-based approach is needed—one that recognizes turfgrass not simply as a water-using plant material, but as a functional component of climate-resilient landscapes that can simultaneously support carbon storage, atmospheric cooling, and long-term sustainability.

Carbon Sequestration Pathways in Turfgrass Systems

Carbon sequestration in turfgrass systems is driven predominantly by belowground processes that promote the accumulation and stabilization of soil organic carbon (SOC). Because turfgrasses are perennial species with dense, fibrous root systems and sustained productivity over long periods, they facilitate continuous inputs of organic carbon to the soil. Once established, these systems typically experience minimal soil disturbance, allowing carbon pools to persist and accumulate over time.

Root-derived carbon constitutes a substantial portion of SOC inputs in turfgrass systems. Fine root turnover, rhizodeposition, and microbial assimilation of root exudates contribute organic matter directly to the soil matrix, where carbon can be physically protected within soil aggregates or chemically stabilized through interactions with mineral surfaces (Qian & Follett, 2002; Kaye et al., 2005). The absence of regular soil disturbance in turfgrass systems reduces the exposure of protected carbon to microbial decomposition, enhancing long-term carbon retention relative to many disturbed or intensively managed land-uses.

Additionally, some routine turfgrass management practices do strongly influence these sequestration pathways. For example, returning grass clippings increases organic matter inputs and supports microbial activity, while nitrogen fertilization can enhance net primary productivity and belowground carbon allocation when applied at moderate rates (Qian et al., 2003). In water-limited regions, irrigation sustains plant growth and microbial processes, indirectly facilitating SOC accumulation by maintaining root turnover and biological activity.

Several studies have demonstrated that turfgrass systems contain SOC stocks comparable to or greater than those of adjacent native or agricultural soils, particularly as management duration increases (Pouyat et al., 2009; Raciti et al., 2011). These findings underscore the capacity of turfgrass systems to function as effective soil carbon sinks within urban landscapes, where opportunities for long-term carbon storage are otherwise constrained. Collectively, the persistence of perennial root systems, limited soil disturbance, and management-mediated carbon inputs position turfgrass as an important component of urban carbon sequestration strategies (Wang et al., 2022).

Long-Term Studies and Field Measurements

Field-based research provides strong evidence that turfgrass systems can accumulate and retain substantial amounts of SOC, particularly when managed over long periods of time. Early work by Qian and Follett (2002) using long-term soil testing datasets demonstrated consistent increases in SOC under established turfgrass compared with baseline conditions, highlighting the capacity of these systems to function as carbon sinks rather than transient carbon pools. These findings were among the first to challenge the assumption that intensively managed turfgrass soils are inherently carbon neutral or result in net carbon loss.

Studies in residential and urban landscapes further support this conclusion. Pouyat et al. (2009) reported that SOC stocks in residential lawns were often comparable to, or greater than, those of adjacent native soils, particularly in surface soil horizons where turfgrass root density is greatest. Similarly, Raciti et al. (2011) found that residential soils with turfgrass cover accumulated carbon and nitrogen over time, with SOC stocks strongly influenced by management history and length of time since establishment.

Golf course studies provide additional insight into the long-term sequestration potential of intensively managed turfgrass areas. Selhorst and Lal (2011) documented substantial SOC storage in golf course fairways and roughs, with carbon stocks increasing with turfgrass stand age and management intensity. These systems, despite frequent mowing and fertilization, exhibited net soil carbon gains due to continuous root inputs and minimal soil disturbance.

More recently, a comprehensive meta-analysis by Phillips et al. (2023) synthesized decades of field measurements across turfgrass systems and concluded that turfgrass sequesters carbon for decades, reaching a state of carbon equilibrium (a natural occurrence in all biological systems) around 50 years. This means that carbon capture continues in turfgrass ecosystems for multiple decades. Collectively, these field studies demonstrate that turfgrass soils—across residential, recreational, and institutional settings—can serve as durable carbon reservoirs, particularly when maintained under consistent, long-term management regimes.

Modeling Carbon Dynamics in Turfgrass Systems

Ecosystem modeling has played an important role in advancing understanding of carbon dynamics in turfgrass systems, particularly where long-term field measurements are limited or logistically challenging. Process-based models, most notably the CENTURY model, have been adapted to simulate soil organic carbon dynamics in managed turfgrass by incorporating turfgrass-specific parameters such as perennial growth habit, clipping management, fertilization, and irrigation (Bandaranayake et al., 2003; Qian et al., 2003). Such models have allowed researchers to evaluate carbon sequestration trajectories over decadal time scales and to assess the relative influence of cultural management practices on SOC accumulation.

Modeling studies consistently indicate that turfgrass systems have the potential to accumulate SOC following establishment, with the greatest gains occurring during the first several decades as soils approach a new equilibrium (Bandaranayake et al., 2003). Simulations suggest that practices such as returning clippings, maintaining moderate nitrogen fertilization, and minimizing soil disturbance enhance net carbon storage by increasing belowground biomass production and organic matter inputs (Qian et al., 2003). Irrigation, particularly in water-limited climates, is also shown to indirectly support SOC accumulation by sustaining plant productivity and microbial activity (Pahari et al., 2018; Zhang et al., 2013).

At broader spatial scales, national modeling efforts have incorporated turfgrass into urban and suburban carbon budgets. Milesi et al. (2005) estimated that turfgrass ecosystems represent a significant component of terrestrial carbon cycling in the United States, emphasizing their cumulative impact due to extensive land coverage. While model outputs are sensitive to assumptions regarding management intensity and climate, they generally align with empirical field observations, reinforcing the conclusion that turfgrass systems can function as long-term soil carbon sinks under appropriate management.

Cool-Season vs. Warm-Season Turfgrasses

Cool-season and warm-season turfgrasses differ in their photosynthetic pathways, optimal growing temperatures, rooting characteristics, and management requirements, all of which influence their potential for SOC sequestration. Cool-season species, such as Kentucky bluegrass and perennial ryegrass, dominate temperate regions and typically exhibit peak growth during spring and fall. These grasses maintain active root systems for much of the growing season, which support SOC accumulation (Qian & Follett, 2002).

Warm-season species, including bermudagrass and zoysiagrass, are more common in southern and transitional climates and exhibit peak productivity during the summer months. Their extended growing season and often deeper rooting systems can promote substantial belowground biomass production, suggesting strong potential for SOC sequestration under favorable conditions (Milesi et al., 2005; Wang et al., 2022). However, warm-season turfgrass management may include practices such as cultivation and overseeding, which may influence long-term carbon stabilization depending on intensity and frequency.

Comparative field studies directly contrasting cool- and warm-season turfgrass SOC dynamics are limited. Nonetheless, both grass types have demonstrated the capacity to accumulate carbon when soils are minimally disturbed and cultural practices that simulate growth are optimized (Bandaranayake et al., 2003; Townsend-Small et al., 2010). Climate also plays a critical moderating role, as temperature and moisture regimes strongly regulate microbial activity and carbon turnover rates.

Overall, existing evidence suggests that both cool- and warm-season turfgrasses can function as effective soil carbon sinks, but sequestration outcomes are highly contextual. Species selection, climate, and management practices must therefore be considered together when evaluating turfgrass contributions to carbon storage and urban climate resilience.

Carbon Costs, Tradeoffs, and System Boundaries

Evaluating carbon sequestration in turfgrass systems requires careful consideration of system boundaries and the distinction between gross soil carbon gains and net greenhouse gas balances. While numerous studies document substantial SOC accumulation under turfgrass, these gains must be interpreted alongside the carbon costs associated with establishment and maintenance. Inputs such as fertilizer production, irrigation energy use, mowing equipment, and other management activities contribute greenhouse gas emissions that can partially offset soil carbon sequestration benefits (Kaye et al., 2005; Townsend-Small et al., 2010).

Nitrogen fertilization represents a particularly important tradeoff, as it can enhance plant productivity and belowground carbon inputs while simultaneously being a large source of greenhouse gas emissions (carbon dioxide associated with synthetic nitrogen production and transportation, and nitrous oxide resulting for improper application (Haxha and Christensen, 2018; IPPC, 2019).. Similarly, irrigation supports biomass production and microbial processes but carries indirect carbon costs tied to energy consumption, especially in arid regions (Wang et al., 2022). As a result, net carbon outcomes vary widely depending on management intensity, climate, and energy sources.

System boundaries are also critical when comparing turfgrass to alternative land covers. Turfgrass removal may reduce direct maintenance emissions, but replacement with artificial turf, gravel, or sparsely vegetated landscapes can eliminate opportunities for soil carbon storage altogether and may introduce new embodied carbon costs through materials production and installation (Townsend-Small et al., 2010). Studies of residential landscapes further indicate that long-established turfgrass soils often represent stable carbon pools, and disturbance during conversion can lead to carbon losses that are rarely accounted for in conservation analyses (Raciti et al., 2011).

Therefore, a comprehensive assessment of turfgrass carbon dynamics requires integrated accounting frameworks that capture both soil carbon sequestration and associated emissions. And such analyses are essential for determining whether turfgrass management strategies contribute positively to climate mitigation and long-term urban carbon resilience (Wang et al., 2022).

Management Implications and Practical Takeaways

Management decisions play a significant role in determining whether turfgrass systems function as long-term SOC sinks because practices that maintain continuous plant growth, enhance belowground carbon inputs, and limit soil disturbance consistently support greater carbon retention. Returning grass clippings is one of these practices, as it increases organic matter inputs and fuels the microbial processes responsible for carbon stabilization without increasing fertilizer requirements (Qian et al., 2003). Maintaining turfgrass at higher mowing heights will also increase carbon sequestration rates (Hamilton, 2024). Life cycle analysis has also determined that electric mowers produce a lower net emission of greenhouse gases (Sivaraman et la., 2004; Saidani et al., 2021).

Turfgrass fertility programs should emphasize moderate nitrogen inputs that sustain productivity while avoiding overapplication that can elevate greenhouse gas emissions or accelerate organic matter decomposition. Organic fertilizer sources reduce carbon dioxide emissions associated by synthetic nitrogen production (Haxha and Christensen, 2018). Properly used controlled release fertilizer can reduce nitrous oxide emissions compared to quick release fertilizer (Braun and Bremer, 2018).

Minimizing soil disturbance is equally important. Turfgrass removal, frequent renovation, or aggressive cultivation can disrupt physically and chemically protected carbon pools, leading to carbon losses that may take years to recover. In contrast, properly timed core aeration can relieve compaction and improve soil function while preserving long-term SOC pools. In arid and semi-arid regions, irrigation management is also a key consideration as maintaining adequate, efficient irrigation supports root growth and microbial activity necessary for carbon inputs while limiting the indirect emissions associated with water delivery (Wang et al., 2022).

From a broader perspective, turfgrass carbon management should be integrated with water conservation, traffic tolerance, and landscape function goals rather than treated as a standalone objective. When thoughtfully selected and managed, turfgrass can contribute to multiple ecosystem services simultaneously, including soil carbon storage, atmospheric cooling, and landscape resilience. These co-benefits underscore the value of management strategies that both optimize turfgrass performance and support long-term environmental sustainability (Phillips et al., 2023).

Conclusions

The current body of research presented demonstrates that well-managed turfgrass systems can function as meaningful and persistent soil carbon reservoirs within the ornamental landscapes that exist in urban and suburban environments. Through continuous belowground carbon inputs, minimal soil disturbance, and appropriate management, turfgrass areas can accumulate and retain soil organic carbon over decadal time scales. These carbon benefits, when considered alongside other ecosystem services like atmospheric cooling, stormwater infiltration, and soil stabilization, position turfgrass as a central component of climate-resilient landscapes.

And while turfgrass management practices do involve carbon and water tradeoffs, these can be mitigated through thoughtful species selection, efficient irrigation practices, and moderate fertility programs. Going forward, research that integrates carbon sequestration, water use, and climate adaptation across diverse regions will be essential for refining the best management practices that optimize carbon sequestration. A balanced, evidence-based approach recognizes turfgrass’s potential to contribute to both climate mitigation strategies and long-term urban resilience.

References

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Braun, R.C. and D. J. Bremer. 2019. Carbon sequestration in zoysiagrass turf under different irrigation and fertilization management regimes. Agrosystems, Geosciences & Environment 2(1):1-8.

Braun, R.C. and D.J. Bremer. 2018. Nitrous oxide emissions in turfgrass systems: A review. Agronomy Journal 110(6):2222-2232.

Buendia, C., K. Tanabe, A. Kranjc, J. Baasansuren, M. Fukuda, S. Ngarize, A. Osako, Y. Pyrozhenko, P. Shermanau, and S. Federici (Eds.). 2019. Ch. 11: N2O emissions from managed soils, and CO2 emissions from lime and urea application. 2019 Refinement to the 2006 IPCC Guidelines for National Greenhouse Gas Inventories. Volume 4: Agriculture, Forestry and Other Land Use. Intergovernmental Panel on Climate Change. https://hdl.handle.net/10568/112778.

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Table 1: General plant and turfgrass systems soil carbon and cultural practice greenhouse gas emissions relationships [adapted from Wang et al. (2022) and Phillips et al. (2023)].

Soil carbon will increase when converting the following land use systems to turfgrass

– bare soil and desert

– grassland and shrubland

– pasture and crop land

Soil carbon levels ranked by turfgrass type

– lawns > golf course fairways and roughs > putting greens and athletic fields

Top three cultural practices with the highest greenhouse gas emissions ranked from highest to lowest

– quick release nitrogen > fossil fuel mowers > irrigation pumping (highly variable depending on climate)

Methods to minimize greenhouse gas emissions and soil carbon loses

– return grass clippings, increase mowing height, use electric mowers

– reduced fertility rates per application, slow-release fertilizer, organic fertilizer

– applying irrigation based on evapotranspiration or soil moisture levels