A recent study suggests that soil bacterial communities can withstand human urine just as well as they do synthetic fertilizers, making the idea of using urine as fertilizer for crops a practical option.
Researchers found that even when large amounts of one-year stored urine were applied, it had minimal effects on soil bacterial communities, pH levels, and salinity.
Interestingly, the study noted that using urine as fertilizer led to a greater presence of nitrifying and denitrifying bacteria compared to synthetic options, indicating that urine-based fertilization could potentially release more nitrogen oxides.
The findings, published in Applied Soil Ecology, emphasize the need for additional research on the long-term impacts of using urine for fertilization, specifically concerning nitrogen oxide emissions and soil salinity levels.
Co-author Manon Rumeau from the University of Birmingham remarked, “Our research underscores the potential of recycling human urine to promote sustainable agriculture, lessen wastewater pollution, and reduce dependence on synthetic fertilizers. Properly stored urine can be safely used in farming systems without harming soil microorganisms.”
Fresh human urine consists of 95% water, with the remaining 5% including amino compounds, such as urea and creatinine, organic anions, and inorganic salts, making it a valuable source of nutrients for plant development.
Interest in utilizing human urine as a fertilizer has grown, but this study marks a significant advancement in understanding its effects on soil functions and microbial life.
In the study, scientists fertilized spinach plants using two different dosages of stored human urine, comparing the results with synthetic fertilizer and an unfertilized water treatment, all conducted in controlled soil tanks in a greenhouse.
After 12 months of storage, the urine showed a reduced microbial population but maintained a few common bacterial strains. This storage period, which increased the urine’s pH to around 9 (compared to 6.5 for fresh urine) and boosted its ammonia levels, was deemed effective in neutralizing most human pathogenic bacteria and degrading extracellular DNA. The bacterial communities in the soil were largely unaffected by the urine application, with only 3% of microbial groups showing any changes, and the high salt content of the urine had negligible impact on these communities.
