Researchers from Wageningen University have shown that urine, in the form of the mineral struvite, can be used as a fertilizer for growing crops on Mars and the moon.

Although it may still be some time before the first human sets foot on Mars, researchers are already busy speculating whether we could live on this and other planets. And there are more obstacles to that than it lack of oxygen. The planet is on average about 220 million kilometers away from us, so a one-way ticket easily takes six months. If we really visit the planet for a longer period of time, we will have to take a lot of supplies with us. Unless we could grow food on site.

And that is exactly what the research team of the Wageningen University in collaboration with it B.A.S.E. project research into, through their project ‘Food for Mars and Moon’. The team is investigating how crops can be grown on Mars and the moon, using the resources available there: regolith (loose, often weathered material on the surface of a planet or moon) and ice. Because real Martian and lunar regolith on Earth are respectively unavailable and scarce, the researchers used simulants that mimic the composition and texture of these materials to investigate how they could best grow crops on them.

BASE project: moon/Mars dome as a testing ground
The recently started BASE project focuses on building a lunar/Mars dome that contains all the necessities to grow crops indoors. This dome serves as a research facility to test innovations and collaborate in a circular system. The blueprint for this can be applied to Mars, the moon, but also on Earth, for example in deserts or at the South Pole.

Fertile soil
And that is quite a challenge. The soil of Mars and the moon are not known to be very fertile. Regolith naturally contains little ammonium, nitrate and phosphate and other essential plant nutrients. In order to grow crops there, the subsoil must be improved. A closed and sustainable agricultural system is crucial, the researchers say. In the past, the research team has succeeded in growing various crops on regolith simulants. Including potato, carrot, pea, tomato, cress and radish. But this was not a circular process and would therefore not be sustainable in the long term. This project therefore wants to focus on making food production completely circular, ultimately including pollination by insects and the use of bacteria, fungi and worms.

Struvite as fertilizer
And surprisingly, that process also involves urine. “And it comes from mobile toilets at festivals in Amsterdam,” says lead researcher Wieger Wamelink. The useful substances from that urine were used in this research to grow green beans on the fake Martian and moon soil. Successfully. The only problem: regolith (and therefore also the simulants) can contain traces of toxic metals that can end up in the plants. The researchers have therefore not yet eaten the green beans grown. The fertilizer ‘struvite’ (a pure mineral that can be extracted from urine and mainly consists of magnesium, ammonium and phosphate) is also not yet officially permitted as a fertilizer for food crops.

But that could be about to change. “With this research we have shown that struvite can be an excellent fertilizer,” says Wamelink. “By using struvite from urine, we can close one of the links in the golden circle of crop production.” Not only on Mars and the moon, Wamelink emphasizes, but also here on Earth. “This way we can reuse human urine in a safe and efficient way. This stimulates plant growth and can significantly increase yields.”




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