If you were ever seriously considering building a long-term staffed moonbase then, sooner or later, someone is going to ask what will the people living there eat? Shipping food ready to eat is a massive task, even to keep a few people alive. It would be much better if people could grow food in lunar soil. There is a problem with that idea though. The moon doesn’t have soil, it has regolith, broken rock pounded into tiny fragments by repeated impacts. Boyang Liao and colleagues in China examine a technique that might familiar to anyone who’s read The Martian.

There’s a scene in The Martian where Mark Watney uses human waste to provide something for potatoes to grow in. Liao and colleagues suggest something similar. They argue that a lunar base will be a closed environment, and so what will you do with human waste and plant scraps? They asked if you could use organic waste, mixed with regolith, to create a lunar soil. To find out, they created an experiment, They fermented a mix of lunar soil simulant with solid waste of the kind they expect to be produced by a lunar base. They then grew wheat in the mix, from seed to harvest, to see how it would grow.

The organic material had a surprisingly potent effect. Even if the researchers added just one part of waste to a thousand of lunar soil simulant, the wheat’s shoot growth increased by around 180% and seed production by doubled compared to the unimproved lunar soil simulant. But things took a strange turn when more waste was added. Despite having more nutrients available, the plants grew less. The problems for the plants were two-fold.

First, the plants were dealing with microbes. Proteobacteria weren’t a problem. These are helpful, particularly with Nitrogen fixation into the soil. A happy plant is able to produce exudates from the toots which, in turn, keeps these bacteria happy. However, there were also other microbes in the soil. Bacteroidota and Firmicutes are specialists at breaking down lignocellulose, a major component of the plant cell wall. When the cell is already dead, the microbes have a useful role in recycling nutrients back into the soil. The problem was, when the waste ratio was increased, these microbes started attacking the live wheat cells. In small concentrations, the wheat and Proteobacteria were able to deal with the Bacteroidota and Firmicutes, but at higher concentrations they were overwhelmed.

Fungi were a similar problem. The organic waste had fungal spores. These can cause problems for plants, but in tiny concentrations they were manageable. When the waste was added in greater concentrations, so too were fungal spores.

Alone, that would suggest that the wheat would not be able to tackle a lot of the waste. However, Liao and colleagues found that may change of time. They found that the wheat was not a passive victim of the bacteria. The exudates it released from its roots cultivated the beneficial bacteria so that, over time, the balance of microbial population shifted strongly in their favour. The next harvest will benefit of the curation of microbes by the previous crop. So the best way to grow wheat on the moon will be to grow wheat on the moon, which sounds tautological.

This is all well and good, but does it matter? We’re not going to Mars and, given current form, we’re not going to the Moon.

It does.

If money is your thing, there’s a cash incentive to have the ability to farm on the moon, even if your farm is elsewhere. The same techniques that make lunar farming possible can be applied to vertical farms and urban agriculture. This would allow farms to reduce their geographical footprint massively. And there’s a lot of money in this. The global Controlled Environment Agriculture (CEA) market is projected to grow from $54.56 billion in 2025 to $140.77 billion by 2032. If you’re not entirely alongside the idea of techno-agriculture tycoons, there are other uses.

Agriculture uses a massive amount of water. The World Wildlife Fund estimates it’s almost 70% of the planet’s fresh water. If you could create a circular CEA system, like you would have on the moon, that would relieve a huge pressure from humanity, make forthcoming droughts less harmful to us and release more water for the rest of nature to cope with drier times.

There are additional features that would help conservation. Understanding microbes would open up biological solutions for problems where we currently use chemicals. If the environments are controlled then, fertilisers and pesticides shouldn’t be spreading beyond our farms. And, beyond the point of view of farming, it may also open up opportunities for more eco-friendly waste management.

Unless it’s possible to prevent rockets blowing up before they safely land on the moon, then the idea of a lunar farm is just moonshine. But the spin-offs of a extra-terrestrial farm that never leaves the planet could have a big pay-off for us here.

READ THE ARTICLE

Liao, B., Yao, Z., Feng, J. and Liu, H. (2025) “Wheat rhizospheric microbial network’s consistent modular pattern in improved lunar soil simulant accompanied with fungal withdrawal,” Acta astronautica, 235, pp. 475–484.: https://doi.org/10.1016/j.actaastro.2025.06.018.

Cover image: Artist’s impression of a lunar farm using clip-art. Almost certainly not what the paper’s authors had in mind.