Earthworms for Mars: chew where no worm has chewed before.

Those who have seen the movie ‘ Dune’ from David Lynch may be able to imagine what we are currently trying to accomplish: growing worms on Mars or the moon. The worms we are going to use are a bit smaller and a lot less violent than those in the movie, although they have creepy names like Lumbricus terrestris or Eisenia fetida. They can be found everywhere in the soil - the first pilot experiments were carried with worms from my own garden! But why worms?

To be able to grow plants in Martian or moon soil we need nutrients, e.g. originating from manure or human poop. A part of these nutrients can originate from the plant parts that we do not eat, such as tomato leaves, stems or potato leaves. However, the nutrients still need to be released from this dead organic matter. Even though bacteria could do this job by breaking down the organic matter and releasing the nutrients, the dead plant parts are a bit too big and chunky for them to do this efficiently. This is where our worms come in! Worms are the perfect intermediary for this job. They consume the dead plant parts, chew them into small parts, and mix them with the soil that they also ‘eat’. This makes it lot easier for bacteria to break down the organic matter further; both worms and bacteria are necessary for an efficient break down of organic matter.

But the worms don’t only do that. They also make burrows in the soil, which makes it easier for water to enter the soil. In this way, the worms help to solve one of the main problems of the very hydrophobic moon soil simulant. When water is poured on the soil, it stands for a long time on the surface of the soil. Water leaks much easier and quicker in the soil due to the worms. The burrows that the worms dig let the water stream in the soil where it also can be stored. The effect of the worms was already visible in our first pilot experiment; it was evident that the water flowed right into the soil. Another big advantage of the burrows is that it provides the root zone easier access to air and thus oxygens. Roots need oxygen for their processes to function properly. Also, part of the bacteria and fungi also need oxygen for their growth. We thus expect the worms to make a huge influence on the growing process, one of which being a higher crop yield. The list of what we need to bring to Mars or the moon is thus extending; not only the seeds of the plants and pollinators, but we also need bacteria and worms!

Story contributed by Wieger Wamelink, a Senior Ecologist at Alterra (Twitter: Wamelink_wieger).

More Information:

Image 1: Here some of the Earth worms from the experiment

Image 2: Here is an example of a sand worm

Image 3: Here are some more worms from the experiment!