A project is under way to develop a novel fertiliser made from human urine to help farmers move towards a sustainable future,

NPK Recovery, a Bristol-based start-up, is developing a system to recover critical nutrients from urine, including nitrogen, phosphorus and potassium, and put them to use as a fertiliser.

The team is working towards a demonstrator system with their partners Peequal, a chemical-free female urinal company, and a network of UK festivals to source their waste feedstock.

See also: UK research discovers protein that could cut fertiliser use

Hannah Van Den Bergh, founder of NPK Recovery, explained the steps behind the development of natural, urine-based fertiliser.

“We collect the urine from Peequal’s urinals, testing it for nutrient content, pathogens and pharmaceuticals before we turn it into a fertiliser,” she said.

“Returning urine to the field helps close the nutrient cycle and uses a waste product to grow crops, instead of these nutrients being lost or becoming a source of pollution as they pass through the UK’s already overwhelmed sewage systems.”

Urine efficacy

A number of studies have already proved the efficacy of human urine as a fertiliser, but delivering this at the scale farmers need is one of the key challenges NPK is seeking to explore, partnering with the Royal Agricultural University and Agri-Epicentre.

UK farmers use about 2.4m tonnes of fertiliser each year, mostly nitrogen-based urea or ammonium nitrate (AN), with 60% of UK fertiliser imported from overseas.

But many farmers want to reduce their reliance on bought-in fertiliser.

The researchers are looking into processing urine into a fertiliser product on or near farm sites.

The urine feedstock can be collected nearby, with this model helping reduce the embedded carbon and greenhouse gas emissions associated with AN and urea, which are both imported into the UK.

The UK produces and disposes of an estimated 100m litres of urine every day, which contains valuable nitrogen, phosphorus and potassium​.  

Support

Agricultural consultant Green Square Agro Consulting are supporting NPK Recovery with its research into novel fertilisers.

“It won’t be possible or necessary to collect all the urine produced in the UK, and this isn’t seen as a replacement for all synthetic fertiliser,” said Mike Lee, an agronomist and director of Green Square Agro Consulting.

But he added: “It will add to the mix of sustainable solutions available to UK farmers.”

The two-year project is being funded by Innovate UK and the Co-Op Carbon Innovation Fund.