An Ancient Maya Practice Could Be the Key to Growing Vegetables on Mars

More than likely, Martian settlers will need to grow their own food.

Researchers are now exploring how best to optimize crop yield on Mars using intercropping, a technique perfected by Maya farmers centuries ago that involves growing multiple plants in close proximity to one another. Their findings—published this month in the journal Plos One—could not only benefit the pioneers who end up colonizing the Red Planet, but also farmers here on Earth amid a rapidly changing climate.

Building upon past research, scientists at Wageningen University & Research in the Netherlands conducted greenhouse experiments that mimicked the conditions of similar structures that could eventually be built on Mars.

Inside the greenhouses, they filled pots with a mixture of rocks, dust and sand, known as regolith, that simulates Martian soil. Separately, they also filled some pots with standard potting soil and some with river sand. They added a small amount of organic soil to both the regolith and river sand pots to help improve water retention and root growth.

Then, they planted peas, carrots and tomatoes in each of the different soil types, both on their own (a practice known as "monocropping") and together (intercropping). Past research had shown that these three crops could grow in Martian regolith, which allowed the team to focus specifically on their questions about intercropping. Peas, carrots and tomatoes are also promising Mars crops because they are high in beta carotene, vitamin C, antioxidants and other nutrients that are typically reduced or destroyed during dehydration.

In the end, they had 12 different experimental treatments. They produced five pots for each treatment, for a total of 60 pots. After 105 days, they harvested their crops and calculated the yield and nutritional value of each plant. Then, they crunched the numbers.

Their results were a bit of a mixed bag. In the simulated Martian soil, tomatoes grew much better when planted alongside carrots and peas. They had more potassium, a higher biomass and a better yield under the intercropping condition compared to being planted alone.

The carrots, meanwhile, produced less biomass and had a lower yield in intercropping compared to monocropping. The peas fared similarly under both conditions.

"It is very important how you select the crop species that you combine, because the tomato did profit from the peas, but the carrot most certainly did not," says study co-author Wieger Wamelink, an ecologist at Wageningen University & Research, to Reuters' Will Dunham. "This was probably due to lack of light. The tall tomato and pea plants did out-compete the carrot by taking light from it."

Even though intercropping in Martian regolith produced varied results, researchers say they can now build on these takeaways while conducting future experiments. These and other future findings might also help growers on Earth, where rising global temperatures and unpredictable rainfall spurred by climate change could make farming more challenging.

More broadly, the paper adds to the growing body of research on our potential Mars' food supply. Elsewhere, scientists are considering whether fly larvae could help add nutrients to Martian regolith, whether vegetables could grow vertically or in pods, and whether it's possible to grow the grains needed to brew beer on the Red Planet.

"If we can unlock the secret to regenerating poor soils while developing a high-yielding, self-sustainable food production system—exactly the goal of Martian agriculture research—we will have found a solution for a lot of the issues we are having here on Earth as well," says study co-author Rebecca Gonçalves, an astrobiologist at Wageningen University & Research, to Popular Science's Laura Baisas.

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