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Could celery help fight climate change?

As part of a UK first wetter farming pilot, The Wildlife Trust for Lancashire, Manchester and North Merseyside are trialling growing a commercial celery crop on a re-wetted peatland field, to combine carbon emissions reduction with financially viable production.

This blog first appeared on the Lancashire Wildlife Trust webiste (June 2022) and thanks to Jenny for giving us permission to reproduce it.

When a peatland is drained and converted to agriculture, the carbon that was stored in the peat oxidises and gets released into the atmosphere contributing to the climate emergency. As part of a UK first wetter farming pilot, The Wildlife Trust for Lancashire, Manchester and North Merseyside are trialling growing a commercial celery crop on a re-wetted peatland field, to combine carbon emissions reduction with financially viable production.

Across the UK, large areas of lowland peatlands have been drained and converted to farmland. In fact, in Lancashire, Manchester & North Merseyside alone, 98 per cent of our lowland peatlands have been lost to drainage, releasing untold amounts of carbon into the atmosphere.

However, re-wetting these areas and growing crops which can tolerate higher water levels could significantly reduce this carbon release, helping to fight the climate emergency. The Wildlife Trust for Lancashire, Manchester & North Merseyside are trialling this form of wetter farming, also known as paludiculture, on a field in Greater Manchester, growing a celery crop. The pilot project is the first time that anyone in the UK has trialled farming traditional food crops on land with a higher water table.

Previously drained, ploughed, fertilised and used to grow crops such as potatoes, all remaining traces of the field’s former life as a bog had been lost – apart from the small amount of peat that was left below the surface. To protect the remaining carbon that is locked up in the peat requires getting that peat wet again. And this is where wetter farming comes in.

How does wetter farming work?

Historic field drains and drainage ditches on the field have been blocked and a series of bunds have been installed. Bunds are low walls of compressed peat which form a watertight barrier, ensuring that water is no longer lost from the area, getting the peat wet again and keeping the water table at between 10cm and 50cm below the surface.

Keeping the peat wet protects its remaining carbon from being released; the challenge is then to find plants which like growing in the wet and acidic conditions that this creates.

Lancashire Peatlands Initiative Project Manager, Sarah Johnson, said; “We know that the current drainage and intensive agricultural use of our lowland peatlands is unsustainable, especially as we are facing a climate emergency. Annual emissions from UK peatlands is estimated at 18.5 million tonnes of carbon dioxide equivalent, the same as produced by nearly 4 million cars in a year, or 5 coal fired power stations! So, we know that protecting the remaining soil carbon in our peat is paramount, but we also know that much agricultural land still needs to remain productive.”

For the first stage of the trial we have planted 85,000 small plugs of celery, a vegetable which is known to tolerate wetter conditions. This will later be followed by radishes and typher (bulrushes) which can be used to create insulation and building materials. Different areas of the trial field will also be kept at different water levels to see how the different crops fare.

This is just the start of a three year trial. In future years we may look at other crops, different water levels and maybe the addition of fertilisers. We want to discern what works, what doesn’t, and what gives the best balance between preserving the precious carbon in the peat and providing the most lucrative crop.

How will the results be measured?

We are working with researchers from Liverpool John Moores University to take regular greenhouse gas measurements from the trial site, monitoring how much carbon dioxide and other greenhouse gases are released over time.

Dr Stephanie Evers, Reader in Wetland Ecology and Biogeochemistry, School of Biological and Environmental Science, LJMU, said; "The trials being implemented here represent an exciting and novel step in developing a range of more sustainable land use options for farmers in order to mitigate climate impacts and work towards maximising the carbon storage potential of this sensitive peatland landscape. In collaboration with Lancashire Wildlife Trust, stakeholders and local farmers, LJMU researchers are leading the environmental research and monitoring programme component of this work to assess changes to greenhouse gas emissions, soil carbon dynamics and hydrology of these alternative crops and farming systems."

"We are so excited to be involved in the first trials of this kind and scale in UK lowland bogs and working towards the development of sustainable peatland farming systems. These celery trials represents the first in a number of crops being grown in peat-forming conditions with the aim of developing carbon neutral, or even carbon accumulating novel agricultural alternatives the current unsustainable practices."

We will also be monitoring how the actual celery crop fares. We are expecting that in this first year the yield may be lower than could be expected through traditional intensive agriculture, as we will not be adding any fertilisers, and are monitoring different water tables levels to see which gives the best combination of crop yield and reduction in carbon releases.

We are also working with local farmers and landowners, employing people with local knowledge to undertake some of the work, and listening to their thoughts and suggestions. In this way we can blend our knowledge of carbon reduction and peat preservation with the vital agricultural expertise of farmers.

What next?

Wetter farming is still in its infancy, and may not be the answer for every piece of drained peatland, but if we are going to stop the damaging release of carbon from these areas then we have to find a different way of managing this land type – and ideally one that allows land managers to derive value in the long term.  

Other options could include carbon farming, such as our pioneering approach at the Winmarleigh carbon farm where drained peatlands are re-wet and the ‘crop’ is the carbon emissions reductions that could be funded through a mixture of government subsidies and carbon credit schemes. Alternatively, trials are being conducted into sphagnum farming, which harvests crops of sphagnum moss from re-wetted peatlands which can be used for peat-free growing media in the horticultural industry.

This project has been made possible thanks to funding from Biffa Award. Biffa Award is a multi-million pound fund that helps to build communities and transform lives by awarding grants to communities and environmental projects across England and Wales.

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There is little doubt that celery will grow on wetted areas. The question is how well, whether there is any additional cost in planting and harvesting and whether there is additional risk. I would be interested to see any data on these aspects. If the costs do rise would it be cheaper simply to wet up the peat and grow the celery in a box?

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