Farmed kelp extract seen to boost barley growth in trial
Seaweed is strong candidate to help agriculture sector reduce use of conventional fertilisers
Researchers working on a collaborative project exploring how kelp extracts can enhance nutrient management in farming, have reported promising results from a controlled glasshouse experiment that aimed to determine whether the extracts could improve nutrient uptake under fertiliser-limited conditions.
The trial by the Scotland-based James Hutton Institute focused on mitigations against the effects of nitrogen limitation in barley and phosphorus limitation in beans.
UK farmers are under increasing pressure to maintain productivity while reducing fertiliser dependency. Integrating seaweed-derived supplements could improve nutrient use efficiency, reducing carbon emissions while simultaneously enriching soil fertility.
The project is being led by North Devon seaweed farmer and biotech business Algapelago Marine Ltd, with support from Innovate UK and several leading industry partners, working closely with Scottish kelp cultivator and innovator Atlantic Mariculture Ltd, as well as research partners, the Hutton and the UK Agri-Tech Centre.
Sustainable extraction
It focuses on three key goals: sustainable extraction and preservation of new seaweed biostimulants, demonstrating evidence for improved nutrient use efficiency, and understanding grower needs and market potential.
Initial results indicated that the tested new seaweed extracts all had significant positive effects on barley grain yield at certain nitrogen levels. This is an excellent result...
Dr Gordon McDougall, head of plant biochemistry and food quality group at the Hutton, said: “The glasshouse trial is now completed and initial results indicated that the tested new seaweed extracts all had significant positive effects on barley grain yield at certain nitrogen levels. This is an excellent result, and we hypothesise that this indicates an improvement in how the barley plants assimilate and use nitrogen.
“We are testing this by analysing the plant material for differences in nutrient uptake and the soil samples for changes in microbiota composition.”
Wet processing
Atlantic Mariculture grows kelp on a 15-hectare site at East Oronsay in Loch Sunart, and has taken the lead in developing sustainable extraction and preservation techniques using farmed sugar kelp (Saccharina latissima) as feedstock.
The company, which owns the former Ardtoe Marine Laboratory, Ardnamurchan, has refined several wet processing methods that avoid the need for energy-intensive drying or milling, creating a route to year-round production that minimises waste while maximising recovery of valuable bioactive compounds. By relying on cultivation rather than wild-harvested kelp, Atlantic Maricultureit aims to demonstrate that seaweed-based agricultural inputs can expand sustainably without depleting marine ecosystems.
The company’s innovation manager, Dr Adrian Macleod, said: “As demand for marine biomass continues to grow, seaweed cultivation offers a scalable and sustainable route to meeting future resource needs.
“Cultivation enables consistent quality and supply while actively supporting Scotland’s Blue Carbon Action Plan and the Circular Economy Act 2024. By growing seaweed rather than harvesting it from the wild, we can deliver ecosystem services and create new opportunities for sustainable marine products.”
Interest from farmers
Through interviews with growers, ranging from small one-acre market gardens to 3,500-acre arable farms, the team at Algapelago Marine Ltd has identified widespread interest in on-farm trials, particularly within arable, fresh produce and soft-fruit sectors. Reducing dependence on expensive chemical fertilisers emerged as the most common reason for exploring alternatives.
Martin Sutcliffe, head of agri-systems at the UK Agri-Tech Centre, said: “What this project and market research shows is there is a desire to use seaweed-based biostimulants, but there is still some scepticism from farmers about the ‘how and why’. Grounding the development of these products in sound data and combining this with understanding the needs of the sectors, will help to remove some of these barriers.
“The trials at the James Hutton have clearly given a strong indication that biostimulants can be a part of the solutions to driving up production, increasing yield and sustainability while reducing the sector’s traditional reliance on fertiliser use.”
The barley project, called “Assessing Sugar Kelp Extracts as a Nutrient Management Tool”, is one of two involving Algapelago Marine Ltd.
Another project, called "Optimising low energy extraction of kelp for soil and livestock nutrition", tested a biostimulant extracted from farmed sugar kelp. The biostimulant resulted in enhanced plant growth and a 24% increase in wheat grain yield, as well as a 45% increase in grain number, when applied at the optimal rate (see below).
