Recent research from the University of Birmingham and L’Institut Agro Montpellier has uncovered a sustainable way to enhance agricultural practices: using stored human urine as a crop fertilizer.
This study, published in Applied Soil Ecology (citation below), suggests that urine can serve as an eco-friendly alternative to synthetic fertilizers, with minimal impact on soil health.
Urine as a Fertilizer
Human urine is composed of 95% water, with the remaining 5% made up of valuable nutrients such as urea, creatinine, organic anions, and inorganic salts. These components are vital for plant growth, making urine a potential source of bioavailable nutrients and micronutrients.
According to the study, even after a year of storage, urine fertilization had little effect on soil bacterial communities.
The researchers found that stored urine, which undergoes changes in pH and ammonia concentration over time, can be safely used as a fertilizer without significantly altering soil pH or salinity.
“Stored urine can be safely applied to a plant-soil system without negatively impacting the soil microbiome,” said Manon Rumeau, co-author of the study from the University of Birmingham.
This finding is essential for agricultural sustainability, as it could help reduce dependency on synthetic fertilizers, which are often costly and harm the environment.
Recycling Human Urine – The Study
In the experiment, researchers compared the effects of two doses of stored urine with those of synthetic fertilizers and water-only treatments on spinach crops.
The results showed that soil bacteria were remarkably resilient to urine application, with only 3% of the bacterial groups affected. Furthermore, high salt concentrations in urine had little discernible effect on the overall soil microbiome.
While urine fertilization slightly increased the presence of nitrifying and denitrifying bacteria—responsible for nitrogen oxide emissions—this difference was minimal when compared to synthetic fertilizers.
“Our research highlights the potential of recycling human urine to enhance agricultural sustainability, reduce wastewater pollution, and decrease reliance on synthetic fertilisers,” added Rumeau.
Urine Storage and Safety
One of the key findings of the research was the impact of storing urine for 12 months.
Fresh urine contains various microbiomes, but after a year of storage, its microbiome becomes depleted, with most pathogens inactivated due to the rise in pH (from about 6.5 to 9) and increased ammonia concentration.
This makes stored urine a safer option for agricultural use, minimizing health risks from human pathogens.
Future Research Directions
Despite the positive findings, the authors acknowledge that they need to carry out further studies to explore the long-term effects of using urine as fertilizer, particularly regarding nitrogen oxide emissions and soil salinity over time.
The research team calls for continued exploration into how urine fertilization affects both soil health and the environment in the long run.
The idea of recycling human urine offers a novel solution for sustainable farming. It provides an opportunity to reduce pollution from wastewater systems while giving farmers access to an eco-friendly alternative to synthetic fertilizers.
Citation
Rumeau, M., Pistocchi, C., Ait-Mouheb, N., Marsden, C., & Brunel, B. (2024). Unveiling the impact of human urine fertilization on soil bacterial communities: A path toward sustainable fertilization. Applied Soil Ecology, 201, 105471. https://doi.org/10.1016/j.apsoil.2024.105471