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Carbon Grass – Additional Information

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In 2009, Sports & Spaces Ltd Technical Director Robert Donald was commissioned to build natural sports turf pitches in the arid desert climate of the United Arab Emirates and the humid tropical climate of Brunei. These projects challenged his grass knowledge, which was largely based on temperate season perennial grasses for sport and amenity usage.

Following these projects, he met with grass scientists at Top Green’s Breeding & Research Station in Les Alleuds, France. While there, he learned of their 16-year grass breeding programme, where thousands of different grass cultivars were being crossbred to create hybrids with the most desirable qualities for the grass seed market.

Deep rooting varieties are considered advantageous for:

  • Plant health
  • Nutrient uptake
  • Drought resilience
  • Overall sward toughness and durability

Top Green’s investigation into deep rooting varieties involved the study of soil organic matter contribution, derived from the seasonal ‘shedding’ of the microscopic adventurous root fibres (villi). The propagation of these root fibres significantly added to the soil’s organic content and also provided a food source (glucose) to the microbiological fauna living in the soil matrix.

Robert returned from the research station with a new understanding of the contribution temperate seasonal perennial grasses can make to biosequestration rates and soil structure forming initiatives. He subsequently worked with Howard Wood, Director at Landscape & Sustainable Services, to produce a list of cultivars with specific applications in green infrastructure environments. These cultivars, comprised mostly of bent grasses and creeping fescues, were dubbed Carbon GrassTM.

Wider research

The Global Development and Environment Institute at Tufts University in Boston conducted extensive analyses of grassland biosequestration[1]. The results demonstrate carbon is effectively and incrementally stored within a soil medium for 50 plus years, with annual increases before carbon levels plateau.

Imagine the grass plant biomass is somewhat like an iceberg – one part (the sward) above ground and four parts (the extensive root system) below. If that ratio is maintained and green infrastructure areas are left undisturbed, the soil organic matter (carbon) within those green spaces will incrementally increase for decades.

This soil organic matter can be accurately measured (usually using the preferred acid loss technique test methodology). Measuring and recording stored atmospheric carbon dioxide as a carbon compound in the soils of permanent grassland areas makes carbon offsets, carbon credits, carbon audits and carbon trading available. It also contributes to a ‘low carbon’ economy and can positively impact the global carbon cycle.

The global carbon cycle

The global carbon cycle is complex, encompassing all aspects of carbon production on the planet.

The Carbon Cycle: Soil as the Largest Terrestrial Reservoir

Values are in Gigatonnes C. 

Source: http://earthobservatory.nasa.gov/Features/CarbonCycle/

The cycle is currently unbalanced. Governments are making significant efforts to address this imbalance through environmental mitigation measures such as the Climate Change Act 2008, the Paris Climate Accords and the Kyoto Protocol.

At its simplest level, the global carbon cycle involves identifying carbon sources and subsequent biosequestration. Extensive biosequestration in areas of permanent perennial grassland has attracted significant global focus, as it offers a particularly efficient method of sequestering atmospheric carbon dioxide as solidified carbon compounds within global soil regimes.

The UK’s green infrastructure – urban green spaces, parks, recreations grounds and other publicly accessible managed grassland areas – covers more than 1,100 square miles. Installing Carbon GrassTM as part of greenfield regeneration projects can make our green spaces environmentally greener.

Carbon GrassTM introduction

Local governments and other stakeholders spend more than £500 million per year on grass maintenance. Research has confirmed the benefits of incorporating carbon grasses within the national green infrastructure. Carbon grasses are slow-growing, low maintenance cultivars. They require fewer cuts and retain the ‘green lawn’ effect of managed grassland. They offer greater sustainability through:

  • Highly efficient biosequestration (carbon storage in the soil) – 300% more efficient than traditional amenity grassland varieties
  • Using deep-rooting cultivars to produce improved soil structure formation and aggregation. This enhances the soil’s capability to receive, store and infiltrate excessive rainfall. This strongly aligns with sustainable urban drainage system (SUDS) initiatives and contributes to the mechanical stability and longevity of urban green space areas.

In one year, one hectare of permanent perennial grassland can sequester 85% more carbon within the soil than one hectare of deciduous woodland.

Practical carbon grass implementation is achieved through Sward SwapTM, a process exclusive to Sports & Spaces Ltd. This non-destructive and discreet method of exchanging grass cultivars to introduce carbon grasses in a range of green spaces offers carbon credits and cost savings. The initial cost of Sward SwapTM will be offset over time in reduced costs for maintenance, mowing fertiliser and irrigation (c30% over current maintenance costs).

No ploughing or cultivation is required. No surfaces are disturbed. The existing sward is sprayed with a systemic non-residual herbicide, immediately followed by intensive overseeding of carbon grass cultivars. As the existing sward dies, the new cultivars germinate and grow within the dying sward. This provides an indistinguishable transition from old sward to new perennial grassland.

Seven to eight days after herbicide application, the dying sward starts to discolour and die off. This correlates with the germination period for the new grasses coming through. The old sward provides a physical biological protective germination barrier to the new sward. Once the new sward has reached a height of approximately 30mm, mowing regimes can resume to help develop the sward and create dense grass covering.

Carbon GrassTM and Sward SwapTM won’t solve climate change. But it’s a good place to start.   

For further information, please visit the Carbon Grasses website.

[1] https://sites.tufts.edu/gdae/files/2019/10/ClimatePolicyBrief4.pdf