If and when the day comes that we, the human race, must take to the heavens and settle on some other planet, the first question will be "can we survive there" -- but the second question will be "can plants survive there?"
A new study from a group of German scientists attempted to grow common crops in the same type of soil that’s found on Mars and our own moon, and discovered some pretty intriguing things.
The first difficulty in testing whether we can grow, say, mustard greens on Mars is actually getting some Martian soil. Luckily, there are sediments here on Earth that are compositionally very similar to extraterrestrial soil, usually dust from around volcanoes. For Mars, a bunch of soil was taken from the area between the Mauna Loa and Mauna Kea volcanoes in Hawaii, which is often used for this sort of testing. The moon-like soil is from deposits left by a long-dormant volcano near Flagstaff, Arizona.
The specific crops chosen for the test were picked for a few specific variables: they’re all crops known to thrive in bad soil, and they all have small seeds, so that they’ll deplete their own source of nitrogen quickly and have to rely on the soil itself for nutrients. The plants, including yellow sweet clover, carrots, field mustard, and leopard’s bane, were all planted in pots, kept at healthy temperatures, and watered twice a day with demineralized water (to avoid contamination with nutrients that are found in tap water). The Mars-like and moon-like soils were contrasted with a nutrient-poor Earth soil, taken from below the Rhine River.
You might expect that nothing could grow in volcanic ash that’s basically bereft of the nutrients we assume are needed for plant life, but incredibly, the plants in the Mars-like soil did quite well. The Martian plants out-performed those using the Rhine River soil, though the moon-soil was less accommodating. None of the moon-soil plants survived, due, the researchers think, to the lack of nitrogen.
It’s a fascinating experiment; certainly it’s not a perfect recreation of life on Mars or the moon, but it’s enough to be encouraging. Assuming we’re all happy eating leopard’s bane.