Improving the crop yields of future Martian agriculture

In a controlled greenhouse at Wageningen University & Research, researchers have made a promising discovery. They've identified a method called "intercropping," pioneered by ancient Maya farmers, that significantly improves crop yields in simulated Martian soil.

This technique involves growing different crops together, and in their experiments, researchers focused on cherry tomatoes, peas, and carrots. Remarkably, tomatoes grown through intercropping produced about double the yield compared to those grown alone in the same soil. They also matured earlier and had thicker stems.

Astrobiologist Rebeca Gonçalves, lead author of the study, expressed her excitement: "Since this is pioneering research, where it's the first time that this intercropping technique is applied to space agriculture, we really didn't know what to expect. And the fact that it worked really well for one out of the three species was a big find, one that we can now build further research on. Now it's just a matter of adjusting the experimental conditions until we find the most optimal system. It can be different species, more species, different ratio of species."

The crops were grown in simulated Martian regolith, a near-perfect match to real Martian soil. Beneficial bacteria and nutrients were added, and the greenhouse conditions mimicked those expected on Mars.

While human bases on Mars remain in the realm of science fiction, NASA is actively working towards sending humans there in the 2030s.

Wieger Wamelink, a plant ecologist and CEO of a company developing lunar and Martian greenhouses, emphasised the importance of local food production: "Mars is really far away. A flight now would take about nine months. If you want to live there as humans, you will have to grow your own crops at the site. Flying in food is very costly and also vulnerable. You do not want to end up on Mars without anything to eat, like in the film 'The Martian.' Our main goal is to use as much as possible from the resources at the site."

Intercropping works by cultivating plants with complementary properties that can help each other grow, optimising the use of resources like water and nutrients. The researchers believe the tomatoes benefited from their proximity to peas, which are good at converting nitrogen from the air into a key nutrient.

However, not all crops reacted positively. Wamelink pointed out: "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. This was probably due to lack of light. The tall tomato and pea plants did out-compete the carrot by taking light from it."

Overall, the vegetables grew well, though not as well as in Earth soil. While these Martian vegetables weren't tasted for testing purposes, Wamelink recalled an earlier harvest: "I thought the Martian ones were sweeter than the Earth ones grown on potting soil."

This research marks a significant step towards self-sustaining human colonies on Mars. While challenges remain, the promise of intercropping offers a glimpse into a future where humans can cultivate their own food on another planet.