Ian Marshall: Nature-based water management that keeps farms and rivers healthy
Ian Marshall is turning a water management challenge into an opportunity by working with nature, not against it. His swale–comfrey system slows and filters runoff, improving water quality while supporting thriving farm ecosystems.
Northern Ireland is one of the wettest places in Europe. As rainwater rushes across farmyards and fields, it picks up manure, fertilisers and other contaminants. Too often, this polluted run-off ends up in rivers and lakes, putting fragile ecosystems at risk.
Ian Marshall is a farmer at the heart of a movement in Northern Ireland to turn this challenge into an opportunity. On his farm, he’s deploying nature-based solutions that slow the flow of water and allow it to be naturally filtered by plants. As a bonus, these plants can even be harvested as a protein-rich animal feed – reducing costs while making farming more sustainable.
It doesn’t rain in Northern Ireland, it pours
Water is a constant management challenge for farmers across Europe. In drier regions, the problem is often too little water. In Northern Ireland, the opposite is true: rain comes in torrents. Rainclouds driving in from the Atlantic drop around 1,000 mm of precipitation per square metre every year. (1)
During heavy, persistent rain, farmers need to drain excess water quickly to avoid waterlogged fields and farmyards. But this runoff picks up nutrients, chemicals, sediments, and other substances commonly found on farms.
When agricultural contaminants enter rivers and seep into groundwater, ecosystems suffer – and so do farmers. Flooded or polluted land can lead to fines, loss of subsidies, and even custodial sentences. In 2017, farming accounted for the largest share (30%) of substantiated water pollution incidents investigated by the Northern Ireland Environment Agency. (1)
There is a clear need for solutions that are simple, affordable, and easy to integrate into existing farm landscapes – approaches that protect both the environment and farmers’ livelihoods.
Working with the land, not fighting it
Ian Marshall OBE grew up on his family farm in County Armagh, Northern Ireland. Once a mixed farm with dairy, pigs, sheep, and arable crops, it eventually specialised in dairy and today works with around 220 cows, alongside some cereals.
Beyond the farm, Ian has always been deeply engaged in shaping agricultural policy and innovation. He has served as President of the Ulster Farmers’ Union, was a Senator in the Irish Parliament, and leads Business Development and Policy at the Centre for Advanced Sustainable Energy at Queen’s University Belfast.
With support from collaborators, including water quality campaigner Alan Keys MBE, he designed a nature-based system that reduces water pollution risk – without expensive machinery or high energy use.
The system combines two simple but effective elements: underground swales, which are trenches following the land’s contours, and comfrey plants, planted above the swales. The comfrey’s long roots penetrate deep into the soil, reaching below the base of the swales, where they absorb nutrients from runoff and store them in their leaves. (2)
This setup provides multiple benefits. It slows water flow, reduces topsoil erosion, and filters nutrients before they reach local waterways. At the same time, the comfrey can be harvested as a protein-rich feed for the farm’s cows. It offers protein levels comparable to imported soy feed, with higher calcium and phosphorus, delivering both environmental and economic advantages.
Supporting a rich ecosystem
As well as being relatively simple to implement, the swale/comfrey system is affordable. On Ian’s farm, it cost around €10,000 to install, has no running costs, and has worked reliably for two years. It offers an affordable alternative to Integrated Constructed Wetlands, which can cost up to €120,000 and take land out of production. (1)
Ian’s nature-based solution was a spin-off of the Water Innovation Network, a European Innovation Partnership project on the Ballinderry River. From 2020 to 2023, five on-farm trials tested variations of the system using comfrey and willow for bioremediation. The final report showed improvements in water quality in nearly all cases, proving the potential of simple nature-based solutions to manage agricultural runoff.
The swales are also creating small pockets of restored habitat. Skylarks, ducks, bees, butterflies, dock beetles and wildflowers have been recorded around the sites, along with evidence of otters returning – clear signs of improved ecosystem health.
Farm walks to inspire neighbours
Ian first connected with EIT Food in 2018 through his work at Queen’s University Belfast. “I was fascinated by the way EIT Food brought together academia, business, and industry: areas that too often operate in silos,” he says. (3)
In 2024, he took part in the EIT Food GROW programme, which supports farmer-to-farmer learning and the adoption of sustainable practices. For Ian, it provided the ideal platform to test his nature-based water management system and share it with others.
As part of the programme, he hosted a series of Farm Walks, giving fellow farmers the chance to see the swale–comfrey system in action and discuss the practicalities on the ground. Several have since implemented similar setups – a clear sign of how EIT Food’s peer networks help spread innovations that protect water quality, biodiversity and farm resilience.
Learn about the Comfrey/Closed Swale System at Ian's farm in Northern Ireland in this inspiring video.
“The GROW programme was brilliant because it got groups of people who were farmers, or researchers, or government representatives, to engage, to have dialogue about this means for sustainable agriculture and what this means for the farmers’ role in making sure waterways are protected, cleaner and safer. The really good thing about GROW is that when you bring groups of like-minded people together, it’s not the only subject that they share ideas about – there’s a myriad of other things they’ll discuss and debate.”
Lessons learned for agricultural innovators
- Work with nature, not against it. Instead of building costly infrastructure to move water off the land quickly, Ian used a simple nature-based system that slows, filters and reuses it.
- Learn from your neighbours. Peer-to-peer learning accelerates adoption. Seeing solutions in action – and hearing directly from other farmers – builds confidence and sparks new ideas.
- Design for real-world farming. Effective innovations must fit existing landscapes and workflows. Ian’s swale–comfrey system is low-cost, low-tech and doesn’t require sacrificing productive land – making it practical for farms of all sizes.
Restoring rivers, one farm at a time
Peer-to-peer learning is a powerful driver of change. Farmers are more likely to adopt new practices when they see them working locally, so early innovators need support and networks like those supported by EIT Food to share practical experience.
There is also scope for more joined-up policy. Regional governments should join forces with river authorities to promote nature-based solutions along whole river systems, not just individual farms.
Across Europe, climate change is adding pressure through droughts, heavy rain and unpredictable seasons – but it is also accelerating innovation. Systems like the swale–comfrey approach reflect a broader shift towards regenerative agriculture that restores soils, supports biodiversity and strengthens resilience.
Agriculture is one of the few sectors that can actively sequester carbon. Healthier soils store more of it, so carbon markets and environmental incentive schemes could play a key role in encouraging farmers to adopt soil-building, low-impact practices. Solutions like Ian's are leading the way to a more sustainable farming future for Europe.
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References
- CAFRE: Water Innovation Network Final Report (2023)
- GROW: Improving Water Quality with Comfrey: Nature-Based Solutions on Ian Marshall’s Farm (2025)
- EIT Food: Ian Marshall: Sustainable farming, from soil to society (2025)
