French researchers think they have found a unique natural alternative to chemical fertilisers. Their discovery reduces environmental pollution and helps feed a growing global population, all thanks to an unexpected ingredient: human urine. In fact, synthetic nitrogenous fertilizers increase agricultural production but, if used in excess, they pollute the environment. Also, their prices are on the rise.
So scientists looked elsewhere for a solution to this combination of crises. What are they replacing chemical fertilizers with? With our urine. OCAPI research program coordinator Fabien Esculier, explained: “To grow plants need nutrients, nitrogen, phosphorus and potassium. When we eat, we ingest these nutrients before excreting themespecially through urine”.
For a long time, urban excrement was used in agricultural fields before being replaced by chemical fertilizers. But when these nutrients are released in large quantities into rivers, they are a major source of pollution. Separating and collecting urine at the source means rethink the toilets, the wastewater collection network and overcome some preconceptions.
The separation of urine from toilets has been tested for the first time in Swedish eco-villages in the early 90s, then to Switzerland or Germany. Now experiments are also underway in the United States, South Africa, Ethiopia, India and Mexico. In France, projects are springing up in Dol-de-Bretagne, Paris and Montpellier. The first generation of toilet with urine separator it was considered impractical and unsightly. A new model, however, developed by the Swiss company Laufen with Eawag, has received good reviews.
There are differences in attitudes in countries where urine-based fertilizers have been tested. The acceptance rate is very high in China, France and Uganda, but low in Portugal and Jordan. Since urine is not normally a major disease vector, it does not require heavy handling to be used in agriculture. The World Health Organization (WHO) recommends letting it rest and it is also possible to pasteurize it.
Once collected, the urine must be transported to the fields. But the procedure is still expensive. Several techniques allow you to reduce its volume and concentrate or even dehydrate it. There are many obstacles, with soaring gas prices and the desire of many countries to strengthen their food sovereignty. Despite this, researchers believe that urine is the future of natural fertilizers.