By: Rebecca Boyle, Wired Science Magazine
If we ever decide to colonize Mars, it might be fairly simple to grow crops in that red soil, according to a new study. Mars’ reduced gravity could let us use less water and fertilizer than we do on Earth.
Visions of future space farms usually involve greenery thriving inside hydroponic systems, but as bio-geo researchers Federico Maggia and Céline Pallud note, using old-fashioned soil has plenty of advantages.
Soil-based agriculture can use settlers’ waste for fertilizer; it can sequester carbon and produce oxygen; and it’s a reliable way to biologically filter water, for instance.
The problem is that Mars is not Earth, gravitationally speaking. Gravity affects the rate at which water and nutrients flow through soil, and plants have evolved to these constraints.
Martian gravity is about one-third as strong as Earth’s, meaning water would flow at a slower rate. This could lead to suffocation of microorganisms and roots, along with emissions of toxic gases, Maggia and Pallud write in a study published early online this week in Advances in Space Research.
To study this effect, Maggi, a University of Sydney biogeochemist, and Pallud, a biogeophysicist at UC-Berkeley, simulated both Mars- and Earth-gravity root processes using BIOTOUGHREACT, a model of soil nutrient transport and microbe dynamics developed at the Lawrence Berkeley National Laboratory.
As Wired Science notes, they realized slower water transport is a good thing. Soil under Martian gravity is able to hold more water, so less of it leaches through and is lost, the authors say.
This increased efficiency means you could use a whopping 90 percent less water for Martian irrigation than what you’d need on Earth. You could also use fewer fertilizers, the authors add.
On the flip side, Martian soil allows for faster consumption of oxygen and dissolved organic carbon, which resulted in a 10 percent increase in CO2 emissions.
So once we start terraforming Mars, our agriculture might be more efficient, but we’ll still have to worry about those blasted greenhouse gases.