Ever ponder whether a late-night pee on your lawn or citrus tree is good for the garden?

Researchers at Griffith University's Cities Research Institute (CRI) have embarked on a project to investigate whether converting human pee into liquid fertilizer is economically viable and whether Queenslanders are willing to have it sprayed in public places.

CRI chief investigator Cara Beal described human urine as "liquid gold" and said a "treasure trove" of nutrients was lost every time a toilet was flushed.

"The foods that plants love the most and need to thrive are phosphorus, nitrogen, and potassium," she told ABC Radio Brisbane.

"That's very similar to what's in our urine.

"Millions and millions of dollars a year are spent trying to treat our waste before it goes into receiving waters for acceptable nitrogen and phosphorus criteria.

"But if we can close that nutrient loop it'd be very sensible in terms of sustainability, the circular economy, and looking after our planet a little bit better."

Overcoming the 'yuck factor'

Creating fertilizer involves pulling nitrogen out of the atmosphere and mining phosphorus, which Dr. Beale says are energy-intensive processes that have a large carbon footprint.

Griffith University's research will focus on collecting waste from waterless urinals and specialized toilets able to separate urine from faeces, as well as the health risks of using pee as a liquid fertilizer and how to change attitudes towards recycled human waste.

Urine recycling technology has existed in Europe for decades and has been trialed in Australia, but Dr. Beale says the "yuck factor" has prevented communities from embracing the practice.

"I think you will find that most people have probably naturally increased the fertilizer capacity of their lawns at some point," she said.

"By the time we use it as a fertilizer, it will have the same smell and texture as a normal liquid fertilizer.

"Urine in its natural form is generally sterile unless there's some fecal contamination."

Closing the 'nutrient cycle'

The CRI has partnered with the Brisbane City Council Parklands Service, Queensland Urban Utilities, and the state government to identify potential trial sites.

Dr. Beal said Brisbane's Roma Street Parklands and Victoria Park were promising locations.

"None of this would go ahead without regulatory approvals and good determination that the urine is safe," she said.

"In this day and age there are lots of pharmaceuticals, hormones, and antibiotics that we need to make sure are removed properly so it's safe for application.

"That's some of the work that we'll be doing at Griffith University as well, looking at that health-based risk and how we can close that nutrient cycle in a safe, sustainable and acceptable manner."

SOURCE: https://www.abc.net.au/news/2022-02-02/researchers-pitch-pee-based-fertiliser-trial/100793460