Fermented food waste could allow farmers and growers to return nutrients currently lost to landfill back into the soil, thanks to a startup exploring how hospitality waste could feed into more circular food systems.
London-based Soil Systems is developing a pelletised soil amendment made from fermented food waste collected from restaurants and other hospitality businesses.
The company says the pellets are more nutrient dense than compost or manure, and could offer a way to recycle nutrients at a time when fertiliser prices remain volatile.
Set up in 2023, the company was formed by four friends — Amy Agnew, Emily Benson, Rosie Wesemann and Vanessa Stockley — after Rosie, who runs two restaurants in London, highlighted how much food gets sent to landfill.
Frustrated by food waste and soil degradation being treated as two separate issues, the group began exploring whether nutrients leaving the food system could be returned to soils in a usable form.
“There’s something deeply wrong about scraping food waste into black bin bags and sending it to landfill,” says Emily, whose background is in international sustainable development. “At the same time, soils are becoming more degraded, and it felt obvious that those two problems should be connected.”
From kitchen waste to pellets
Soil Systems’ approach is based on bokashi fermentation, a process that uses microbes to break down organic material through anaerobic fermentation.
While bokashi is already used by some growers and gardeners, untreated fermented food waste can’t be commercialised or easily scaled.
To overcome the problem, the company has worked with experts to find a way to stabilise fermented material, converting it into a pellet that can be put back into the soil.
“The challenge is that food waste behaves differently depending on what’s in it,” says Amy, who also worked in international development. “Oil content, moisture, starch, all of it affects whether it will pellet properly.”
Through repeated small-scale batches and working with an R&D partner, the team has refined their production process to ensure consistency and create a dense pellet designed to be handled and applied in similar ways to other dry soil amendments, such as pelletised organic fertilisers or dried manure products..
The pellet format is designed to make storage, transport and application more straightforward than untreated organic waste. “The value is in the density and consistency,” explains Amy. “You’re not moving water around, and you’re not dealing with something that varies hugely from batch to batch.”
Nutrient density
According to Soil Systems, the pellets are about three to four times more nitrogen-dense by weight than typical composts or manures, and contain high levels of organic carbon, which is important for crop yields, fertility and resilience.
Because the feedstock comes from food waste rather than green waste or livestock manure, the nutrient profile is also relatively rich.
Laboratory analysis has been carried out by an independent commercial laboratory to establish NPK content and confirm the absence of pathogens. The company has also carried out small growing trials with NIAB, comparing a control with two application rates across tomatoes, runner beans, lettuces and dahlias.
While the trials were carried out on small outdoor plots and not designed to be statistically robust, early data showed clear differences between treatments.
“Across tomatoes, runner beans, dahlias and lettuces, the weight at harvest at least doubled, and in some cases tripled,” says Amy. “In the case of runner beans, yields were nearly four times higher by weight, and fruit counts at least doubled in tomatoes and beans. Interestingly, the lower application rate performed best.”
Further trials planned for 2026 will focus more explicitly on soil health indicators, including organic matter and biological activity, rather than just plant growth, she says.
Building technical credibility
The work is being supported by the Rothamsted-led SHAKE Climate Change programme, which is helping Soil Systems move from proof of concept towards pilot-scale production.
To support product development, Soil Systems has worked with several research and technical partners, including NIAB, Harper Adams University and the University of Reading, which have provided trial space, analysis and process advice.
Alongside research partners, Soil Systems is developing pilot supply chains with hospitality businesses and local authorities, including a forthcoming pilot in Camden, London. The project aims to demonstrate a closed-loop system in which food waste collected locally is processed and returned to growers within the same area.
The pilot will also support further product testing across a range of crops and growing systems, helping to define application rates and use cases more clearly.
Scaling production
Rather than building large, centralised processing plants, Soil Systems plans to operate small, modular units close to where food waste is generated. The aim is to keep transport distances short and capital costs relatively low.
This year the company will carry out a series of pilots to refine their operations, processing equipment and the end product. Once trading, by their fifth year they hope to produce more than 2,000 tonnes of pellets using multiple operating units.
“We’re not pretending this replaces manure or digestate at a national scale,” Amy says. “What we’re trying to do is build something that works locally, can be replicated, and grows by adding more small units rather than one big central plant.”
The coming months will also see the business focus on compliance, including achieving end-of-waste status and meeting animal by-product regulations so that mixed food waste can be processed legally.
“This is our pilot year, and the funding from SHAKE will enable us to work with five or six restaurants to carry out the whole cycle of what we’re doing,” Amy says. “From food waste collection through to processing, bagging up the pellets, and then taking it to different partners across the growing spectrum to trial it, it’s an important year of development for us.”
- A UK startup is turning hospitality food waste into a dry, pelletised soil amendment that can be stored, moved and spread like other organic fertilisers.
- The company says the pellets are around three to four times more nitrogen-dense by weight than typical composts or manures, with a relatively rich nutrient profile.
- Early NIAB plot trials on tomatoes, runner beans, lettuces and dahlias showed clear yield differences between treatments, with the lower application rate performing best.
- The business plans to scale using small, modular processing units close to where waste is produced, aiming to keep transport distances and capital costs down.
- Next steps include 2026 pilots to refine application guidance and gather more data on soil health indicators such as organic matter and biological activity, alongside compliance work to legally process mixed food waste.
This article is published as part of Farming Future Food’s Industry Insights series, which is supported by sector partners. The FFF editorial team maintains full independence over content.
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