SOUTHEND, ENGLAND - MAY 26: A general view of portable toilets along the seafront promenade on May 26, 2024 in Southend-on-Sea, United Kingdom. (Photo by John Keeble/Getty Images)
In the last century, synthetic fertilizers have revolutionized agriculture, supporting a global population that might otherwise be halved. However, farmers now face a looming fertilizer shortage that threatens to disrupt agricultural processes and potentially escalate into a global food scarcity crisis. Surprisingly, a solution suggested by sustainably-minded scientists is human urine.
A Fertilized Future
Human urine has been recognized as a viable alternative to synthetic fertilizers for decades. Ancient civilizations, including those in Rome and China, were aware of its benefits. Urine and synthetic fertilizers both contain phosphorus, nitrogen, and potassium—essential nutrients for plant growth. However, the phosphorus required for synthetic fertilizers is becoming increasingly difficult to source, as it is mined and non-renewable.
Without phosphorus, access to fertilizers diminishes, leading to potential food shortages. Urine, however, offers a renewable source of these nutrients. Experts recommend diluting urine before using it on plants to protect roots and shoots.
What Can “Wee” Do?
Jordan Roods, a PhD candidate at the Institute for Sustainable Futures, University of Technology Sydney (UTS), is at the forefront of research funded by the Australian Research Council Hub for Nutrients in a Circular Economy (ARC NICE Hub). This initiative explores innovative methods to convert nutrients in human urine into renewable fertilizers.
“The system isn’t geared towards looking at urine as a resource rather than as a waste product,” says Jordan Roods.
Most wastewater ends up in oceans, contributing to harmful algal blooms or washing up as fat balls on beaches. According to Roods, this represents a missed opportunity for economic and social benefits.
Liquid Gold?
Urine-derived fertilizers could be more sustainable and cost-effective than their synthetic counterparts. The economic benefits are significant, especially considering Australia’s $9 billion annual expenditure on wastewater processing.
“By recycling it and using it as a fertilizer, you’re ticking multiple boxes: achieving food security, reducing water pollution, improving soil health, and creating new market opportunities,” says Jordan Roods.
While urine can be used directly on plants, processing it enhances safety and stability. Labs employ techniques like pasteurization, dehydration, and membrane filtration to transform urine into a viable fertilizer.
What’s the Catch?
Critics raise concerns about antibiotic resistance from urine-derived fertilizers, but experts argue this fear is unfounded. The social taboo surrounding urine as fertilizer presents a more significant barrier. However, processing urine through pasteurization removes pathogens and contaminants, making it safe for crop use.
Jordan Roods emphasizes the importance of decentralized processing to minimize transportation costs. Phosphorite, the mineral form of phosphorus, is only mined in a few locations, while urine is produced everywhere.
Coming to a Loo Near You?
Organizations like the US Rich Earth Institute are developing scalable systems for onsite wastewater recycling, allowing communities to convert their wastewater into fertilizers without leaving the premises. Locally, UTS is testing a portable membrane bioreactor system to process urine on-site.
Despite regulatory challenges, such as those faced by the Environmental Protection Agency in Australia, the potential for urine-derived fertilizers is promising. A 2025 review confirmed their safety and effectiveness, provided pathogens and pharmaceuticals are eliminated.
As lawmakers catch up, it seems inevitable that urine-derived fertilizers will play a crucial role in a sustainable and surprisingly clean future.
