Pilot sites Winmarleigh carbon farm and Little Woolden Moss

A brief tour via:

-Case study Winmarleigh Carbon farm (Main Output)
-Case study Little Woolden Moss companion planting pilot (Main Output)
-Our Fact sheet
-Our Panaroma-solution

Summary Winmarleigh Carbon Farm

The Winmarleigh carbon farm has provided clear data demonstrating the viability of re-wetting and re-vegetating with Sphagnum moss as a means to restore the carbon function of drained lowland agricultural peatlands and reduce greenhouse gas emissions. 

The Winmarleigh carbon farm was created by Lancashire Wildlife Trust on an area of drained lowland agricultural peatland in Lancashire in northwest England. The site was originally lowland raised bog habitat first drained in the 1970’s and mainly used for sheep grazing. This drainage based agricultural land use was causing loss and degradation of the peat with associated emissions of greenhouse gases, and an additional drainage effect on the neighbouring Winmarleigh Moss SSSI. 

To address this, a pilot carbon farm was created, the aim being to re-wet the peat and grow a permanent cover crop of Sphagnum moss. This would protect the existing soil carbon, reducing greenhouse gas emissions and, in time, sequester further carbon through peat formation. 

In May 2020 work started. 10cm of topsoil was removed to reduce nutrients and the existing vegetation and seed bank. Bunding was then installed to divide a 2 hectare area into 8 cells, with irrigation ditches running between them. A further part of the site was used to create a water storage area. A solar powered pump was then installed to power an irrigation system where water could be pumped from the water storage area into the irrigation ditches, controlled by a ballcock system. The aim was to maintain a water table at approx. 10cm below ground level throughout the year. 

150,000 plugs of Sphagnum moss, consisting of a specially chosen mix supplied by BeadaMoss, were then planted in 5 of the cells. They were spaced at 20cm apart with the aim to achieve full Sphagnum cover as quickly as possible. The final 2 cells were planted with Common reed (Phragmites australis), intended to filter irrigation water before it re-entered the drainage system. The Sphagnum was protected during establishment by a thin layer of straw. A further 25,000 plugs of Sphagnum were introduced into any areas of poor growth and a remaining unplanted cell in June 2022. 

Throughout the Care-Peat project, partner Manchester Metropolitan University has measured carbon greenhouse gas emissions and water table depths, as well as other key variables, on both the carbon farm site and a directly adjacent control site of drained and grazed pasture. Measurements were taken monthly for a 2 year period using a Los Gatos greenhouse gas analyser and an on-site weather station. 

Results showed: 

• A reduction in carbon greenhouse gas emissions from the carbon farm compared to the grazed pasture of 88.4% in year 1 and 90.7% in year 2. 
• Methane fluxes were measured and found to be negligible. 
• 2 years after planting the Sphagnum coverage had reached 57% in some areas of the site (full cover is expected by the end of 2024). 
• The water table has been consistently higher on the carbon farm than on the grazed pasture. 

Whilst not being specifically managed for biodiversity, the carbon farm site has started to be colonised by other bog species from the neighbouring SSSI such as Calluna vulgaris, Polytrichum commune and Drosera rotundifolia. Several species of butterflies, damselflies and dragonflies have also been observed which were not previously found on the grazed pasture, along with amphibians and bird species. 

An economic business case has been undertaken for the carbon farm. Potential sources of income could include the sale of carbon credits from the greenhouse gas emissions reductions, government subsidies, grant funding, or corporate support for voluntary, unverified carbon offsets. The set-up costs show that carbon prices of £80 per ton would be required to break even. However, it is believed that farmer’s adopting this approach themselves would incur significantly lower set up costs which could help to make carbon farming more profitable in the future. 

Perhaps an even greater success has been the extensive interest and publicity the carbon farm has generated, helping to raise the profile of peatland restoration and particularly the options available for adopting wetter peatland management techniques. 

Summary Little Woolden Moss

Little Woolden Moss is a former industrial peat extraction site in Greater Manchester in the northwest of England, that is being restored back to lowland raised bog. The companion planting pilot took place on an area of bare peat and investigated the most efficient method of restoration planting, and the effects of planting different species in differing ratios on reducing greenhouse gas emissions. 

Re-wetting works such as ditch blocking and bund installation had already been completed on the 1ha pilot site to help retain higher, more controlled, water table levels. Subsequent subsidence of infilled ditches has created a topography of ridges and depressions across Little Woolden Moss and the pilot site reflects this. 

In March 2020 the pilot site was planted with a mixture of 18,000 (75%) common cottongrass (Eriophorum angustifolium) and 6,000 (25%) hare’s-tail cottongrass (Eriophorum vaginatum) plugs, in clumps consisting of 1 hare’s-tail cottongrass and 3 common cottongrass. 6 months later, giving the cottongrass time to establish over the summer, 10,000 Sphagnum moss plugs were added into the middle of each cottongrass clump. The Sphagnum plugs consisted of 5 different Sphagnum species chosen for their resilience and hummock forming ability which were anticipated could maximise carbon storage. 

A control area of bare peat was also established. 

The pilot came up against a number of issues. Immediately after planting many of the Sphagnum plugs were pulled up by crows. They were re-planted where possible, and bird-deterrent devices employed to reduce further damage, but many plugs were lost entirely, and the disturbance contributed to much of the Sphagnum failing to thrive. 

The pilot site also sloped slightly and was subject to water pooling deeply at the lower end. This caused much of the above-ground plant material to be lost due to wave action. E. vaginatum plants were a little more resilient, having a tighter growth habit, and in some areas E. angustifolium plants showed subsequent signs of regenerating from rhizomes. An overflow pipe was subsequently re-sited to reduce flood water more effectively. 

Monthly monitoring of methane and carbon dioxide fluxes, along with environmental variables of water table depth (WTD), soil temperature, photosynthetically active radiation (PAR) and vegetation growth was carried out by project partner Manchester Metropolitan University. Measurements were taken from both the pilot site and control area. 

Results varied greatly between years 1 and 2 due to flooding and also drought: 

• Due to rapid vegetation growth, there was a significant uptake of carbon in year 1 of 22.41 tCO2eq/ha. This was much less noticeable in the following year however, with the site returning to average emissions of 26.09 tCO2eq/ha. However, in areas where Sphagnum was retained a small uptake of CO2eq was recorded again in year 2. Consistent CGHG benefits are not likely to be observed until the Sphagnum re-establishes.  
• Water table depths were variable across both the pilot and control sites, with the control area being generally slightly higher, possibly due to increased peat depths in that area holding water better. 
• Across the main pilot, in areas not subject to flooding, the Eriophorum species colonised rapidly, with 49.1% and 69.0% cover at 17 months and 31 months after planting respectively. 
• The ratio of E. angustifolium to E. vaginatum cover by November 2022 was 8:2. This is obviously greater than the initial planting ratio of 3:1 and makes E. angustifolium the primary choice for revegetating bare peat areas. 

Conclusions from the pilot site include needing to give cottongrass species more time to establish before introducing Sphagnum, and the need to maintain consistent water levels. These learnings will be shared with other restoration projects to help bring our degraded peatlands back to life. However, the pilot did demonstrate that re-vegetation of a post-industrial extraction site can be achieved rapidly, even on shallow, poor quality peat.