A new study has concluded that bacterial communities in soil are as resilient to human urine as synthetic fertilisers – making the bodily fluid an “eco-friendly” option for crop fertiliser.
A team of researchers from University of Birmingham and L’Institut Agro Montpellier, France published their findings in the scientific journal Applied Soil Ecology.
It looked at the long-term effects of urine fertilisation – particularly regarding nitrogen oxide production and soil salinity (salt content).
The researchers discovered that, even when applied in high doses, one-year stored urine had little impact on soil bacterial communities and produced minimal change in soil pH and salinity.
However, the researchers did discover that using that type of fertilisation increased the relative amounts of nitrifying and denitrifying groups compared to synthetic fertilisers. This means that more nitrogen oxides could be emitted.
Urine as fertiliser
Researchers fertilised a spinach crop with two different doses of a source-separated and stored human urine.
The results were compared with a synthetic fertiliser treatment and a water treatment without fertilisation across four soil tanks in greenhouse conditions.
After 12 months of storage, the treatment had a depleted microbiome but contained few common strains.
Soil bacterial communities were resistant to urine fertilisation with only 3% of groups of organisms impacted. The urine’s high salt concentration had little discernible effect on the bacterial community.
Co-author from the University of Birmingham, Manon Rumeau said: “Our research highlights the potential of recycling human urine to enhance agricultural sustainability, reduce wastewater pollution, and decrease reliance on synthetic fertilisers.
“Stored urine can be safely applied to a plant-soil system without negatively impacting the soil microbiome.”
Fresh urine is composed of 95 % water with the remaining 5% made up of amino compounds, such as urea or creatinine, organic anions and inorganic salts making it a source of bioavailable nutrients and micronutrients for plant growth.
