The soil on Mars may be suitable for cultivating food crops – this is the prognosis of a study by plant ecologist Wieger Wamelink of Wageningen UR. This would prove highly practical if we ever decide to send people on a one-way trip to the red planet. After all, if we are going to live anywhere in outer space in the future Mars stands a good chance of being the place.
In a unique pilot experiment Wieger tested the growth of 14 plant varieties on artificial Mars soil over 50 days. NASA composed the soil based on the volcanic soil of Hawaii. To his surprise, the plants grew well; some even blossomed. “I had expected the germination process to work, but I thought the plants would die due to a lack of nutrients,” Wieger explains. The soil analysis showed, however, that Mars soil contains more nutrients than expected. In addition to phosphorus and iron oxides, the scientist found nitrogen, an essential plant nutrient.
I confess to some skepticism regarding the relevance of these findings to actual plant growth on actual Mars. The experiment used Hawaiian volcanic soil, which has a very different geological history than the Martian regolith, so I’m not sure to what extent it is a good model. Also, if the scientist whipped it up himself, it’s hard to understand how there could be “more nutrients than expected”, or why a surprising result regarding the composition should create optimism that we might see the same thing on Mars.
Plus,there’s some evidence that Martian soil is full of perchlorate and other consequences of UV irradiation, and it’s not clear that these parameters were incorporated into this experiment.
That said, experiments of this general type are of great utility: With an eye toward the future, we should be trying to model the Martian soil and determine how best to convert it into something that Terran plants can assimilate. Hydroponics (and variants like aquaponics, which might be a good way to get some animal protein into the colonists’ diet) will unquestionably be central to early efforts to establish a renewable food source in the early colonies. Subsequently, we might shift from using ready-made (and probably imported) fertilizer substrates to chemically extracting important elements directly from the regolith. But eventually we’ll want to start relying on plants’ natural ability to assimilate nutrients from their growth substrate, and (with the help of bacteria) decompose back into that substrate, to create a true Martian soil cycle. And despite the critiques I offered above, experiments like this are an important start in that direction.