Meet The Pioneer Species
Drawing from Handelsman’s book “A World Without Soil”, students will learn that soil is not just "dirt," but a mixture of rock, water, and life. You can't just drop a tomato seed into raw Martian dust and expect a harvest. You need a "pioneer species" to do the heavy lifting required to be successful. This is an opportunity to reinforce the time span required before these processes can take place. Students can see how lifeless soil on Mars must be carefully constructed at the same time here on earth we are systematically destroying key parts of soil biome which could take decades to repair. During our investigations we determined that Mars has special needs beyond that of simple fertilizers. At this point the student should be understanding the length of time that is required to generate proper soil. We are in a step-by-step building process and every step is critical to minimize the time required to create food crops. To that end, we need to be selective in our pioneer species and what they can provide to the environment. This gives students a chance to investigate how different pioneer species are required for different biomes. In the case of Mars there are several good candidates that provide different benefits to the virgining soil. This is where cyanobacteria can come in not just to remove the perchlorates salt but "de-salt" Martian water, and then they can be processed in an anaerobic digester to create a super-concentrated liquid fertilizer with results that are incredible with just one gram of cyanobacteria can produce enough fertilizer to grow 27 grams of duckweed, a fast-growing, high-protein "super-crop".[15] It is a steppingstone game but once a crop like alfalfa is grown you can crush it up into a powder and mix it back into the regolith as biofertilizer. This process adds the missing nutrients and helps the soil hold water. Experiments show that this "alfalfa-treated" soil can boost the growth of food crops like turnips, radishes, and lettuce by as much as 300%. Students will have already researched nitrogen-fixing bacteria (rhizobia) and mycorrhizal fungi. It may be possible to have student produce a "microbial starter kit" that could be introduced to other sterilized Martian regolith to initiate nutrient cycling. This allows students to experience how chemicals released from living and dead organisms are the key to Earth's fertility in the rhizosphere, where plant roots pump carbon into the soil to feed microbial communities. This truly turns regolith into soil. Since the initial experiment is being completed on a smaller test area and the students are keeping a journal of each success and failure throughout the process it would be an easy process to create a "microbial starter kit" which would make expanding to a larger area easier and quicker to accomplish. In the Martian Soil Plant Growth Experiment, researchers found that adding Rhizobia bacteria and VAM fungi was a total gamechanger. VAM fungi act like a massive extension of the plant's root system, increasing the surface area for taking up nutrients by up to 1,000%.[16] By using these tiny allies, we can utilize the nitrogen already in the Martian atmosphere instead of shipping heavy tanks of fertilizer from Earth. This can lead to other plant species whose job is strictly to develop the soil long term.
- Snake Plant (Sansevieria / Dracaena trifasciata): One of the most adaptable pioneer species for low light. It tolerates deep shade, drought, and neglect.
- Creosote Bush (Larrea tridentata): This is a quintessential native desert pioneer. It thrives in poor soils and low moisture. While it prefers sunlight, its waxy leaves help it survive filtered, low-light conditions.
- Cast-Iron Plant (Aspidistra elatior): Renowned for surviving extreme neglect, this plant is an excellent choice for deep shade and requires very little water once established.
- Mesquite Trees (Prosopis): In absolute desert environments, mesquites act as foundational pioneer trees. They anchor roots deep into the ground, fix nitrogen, and create the microclimate/shade needed for smaller, more sensitive understory plants to eventually grow.
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