If NASA ever manages to make it to Mars (or if Musk beats them all to it), then needless to say it will be fairly necessary to start growing our own food on the alien planet. But as a rocky world that is not blessed with a protective atmosphere, the soil found there is pretty barren, meaning if anything is to grow it’ll need a helping hand from us.
But it is not only organic matter that helps plants thrive, it's all the bacteria and organisms that burgeon in the soil itself, including the humble earthworm. Now, researchers from Wageningen University & Research have shown that these wiggly critters are quite content in simulated Martian soil, so much so that they will even breed. There is still an awfully long way to go before we’re toiling the red sand of Mars, though.
“Clearly, the manure stimulated growth, especially in the Mars soil simulant, and we saw that the worms were active,” explains Wieger Wamelink, who helped carry out the research, in a statement. “However, the best surprise came at the end of the experiment when we found two young worms in the Mars soil simulant.”
Obviously, we don’t have access to Martian soil, so the team got their hands on the simulated soil that NASA uses. This is made by taking dirt from a Hawaiian volcano and mixing it with some taken from the Mojave Desert, before sterilizing it to make sure that it's well and truly lifeless.
Using this substitute, and fertilizing it with pig slurry as a stand in for human poop (we all remember that bit in The Martian), the team were able to grow arugula (rocket) plants in an environment that they say matches what people would likely be living in. Due to the vital role of earthworms on Earth, they also added these to the mix to chomp up organic matter and break it down, before pooping it out. Earthworms also aerate the soil as they burrow about. And to their surprise, the worms started mating.
Now, before we all get ahead of ourselves, this study is still very speculative. The soil is not actually Martian soil, and the methods to grow the plants might in reality be quite far off from what the first humans on Mars will do.
There is no certainty they will use human poop as a fertilizer for a start, as there are risks of spreading pathogens. It's also likely that the first settlers might take samples of Earth soil with them to "seed" the Martian soil. Anyway, we're not going to have to worry about this for another few decades at least.