Human Urine as Fertilizer: Could it Revolutionize Farming?

Scientists say using human urine as fertilizer could help save the planet.

A new study is making waves in the agricultural world, suggesting a surprising but promising way to grow food more sustainably: using human urine as fertilizer. Researchers from the University of Birmingham in the UK and L’Institut Agro Montpellier in France say human urine could be a game-changer, helping reduce greenhouse gas emissions while keeping crops healthy.

Modern farming relies heavily on synthetic nitrogen fertilizers because they’re cheap and effective. But their environmental cost is staggering. Producing and using these fertilizers releases large amounts of carbon dioxide, methane, and nitrous oxide into the atmosphere. Nitrous oxide, in particular, is a heavy hitter in global warming, with a warming potential 265 times greater than carbon dioxide. The agricultural sector’s dependence on these fertilizers has made it a significant contributor to climate change.

Why human urine though? The idea of using human urine as fertilizer isn’t as wild as it might sound. Human urine is 95% water and contains valuable nutrients like urea, creatinine, organic anions, and inorganic salts that plants love. While its nutrient content is well-known, researchers have long wondered how urine might affect the delicate balance of soil ecosystems. Could it harm the beneficial microbes in the soil? Or would it be a sustainable alternative to synthetic options?

To find out, the researchers conducted a year-long experiment with four spinach crops grown under different conditions. Two groups were fertilized with stored human urine at varying doses, one with synthetic fertilizer, and one with just water. After 12 months, they assessed soil health and crop performance.

The results were encouraging. Urine-based fertilizers didn’t harm soil microbes, even at high doses. In fact, they performed just as well as synthetic fertilizers in maintaining soil health. While there was a slight concern about higher levels of nitrous oxide emissions from urine fertilizers, more research is needed to confirm this.

Manon Rumeau, one of the study’s authors and a PhD candidate at the University of Birmingham, summed it up: “Our research highlights the potential of recycling human urine to enhance agricultural sustainability, reduce wastewater pollution, and decrease reliance on synthetic fertilizers.”

The benefits of human urine as fertilizer go beyond just healthier soil. Using human urine has a number of benefits. One, it could cut greenhouse gas emissions. By reducing the need for synthetic fertilizers, farmers could significantly lower their carbon footprint.

It could also save water and reduce pollution. Diverting urine from wastewater systems could ease the strain on treatment plants, which often struggle to handle high nitrogen levels.

Finally, human urine could boost food security. With the right systems in place, urine-based fertilizers could help farmers meet growing food demands sustainably.

While the findings are promising, there are still hurdles to clear before human urine as fertilizer becomes mainstream. Long-term use raises concerns about salt buildup in the soil, which could harm plants over time. Monitoring soil salinity across multiple growing seasons will be crucial to ensuring its sustainability.

Then there’s the issue of nitrous oxide emissions. Early results suggest that urine fertilizers might produce more of this potent greenhouse gas than synthetic options. Tackling this issue will be essential for making the case for widespread adoption.

Economic and logistical challenges are another piece of the puzzle. Collecting, storing, and distributing urine at scale is no small feat. Urban areas where large amounts of human waste are generated could be key to developing cost-effective systems for urine recycling. Innovations in this area could pave the way for cities to turn waste into agricultural assets.

The researchers behind the study are calling for more large-scale trials to explore how human urine as fertilizer performs across different crops and climates. They also want to dive deeper into its long-term impacts on soil health and its practicality for farmers. With further research, this eco-friendly alternative could help shape the future of agriculture.

For now, the idea of using human urine to grow food might take some getting used to. But as we look for ways to combat climate change and feed a growing global population, this unconventional solution might just be what we need to keep both the planet and our plates full.