The technique of intercropping is an ancient method that has been used on Earth for centuries, and is now for the first time being applied to space agriculture too. The technique involves cultivating plants with complementary properties that can aid each other in growth, resulting in higher yields and the optimisation of resources such as water and nutrients. Since the first Martian colonies will be extremely limited on such precious resources, this ancient approach may hold the key to our future on Mars, especially during the first few missions.

The team of researchers included astrobiologist Rebeca Gonçalves, Martian studies expert Dr. Wieger Wamelink, and agricultural systems expert Dr. Jochem Evers. The researchers grew peas, carrots, and tomatoes in a type of Mars regolith simulant (“regolith” being the technical term for a soil that has no organic matter or life present). This Martian regolith simulant, produced by a team of researchers at NASA, is a near perfect physical and chemical match to the real Martian regolith, used by NASA itself to test the rovers that go on Martian missions.

All three species grew well in the Martian regolith, yielding over half a kilo of fresh produce with only a minimum addition of nutrients. However, the research breakthrough came through the fact that one of the species, tomato, performed remarkably better when grown using the intercropping technique compared to the traditional monocropping method, with significant increases in both size and overall yield.

The use of intercropping to save up on resource use can be a game changer for the local production of fresh food in exploration missions, increasing the colony’s food security and self-sustainability, an essential feature for the independence of colonies and for the future of long-term human settlement on Mars and beyond.

“An even greater aspect of this line of research is that all the technology developed for a self-sustainable colony on Mars, which includes soil regeneration techniques and the development of closed self-sufficient and self-sustainable systems, can be directly applied for the benefit of agricultural systems also here on Earth” said lead researcher Rebeca Gonçalves.

Today, 40% of Earth’s agricultural land has been degraded either by human action or climate change [1], affecting about 1.5 billion people worldwide [2]. Space agriculture research can provide critical insights into resilient Earth agricultural practices that can benefit such arid and degraded soils.

In fact, the study carried out a control treatment utilising sandy soil, which has similar properties to degrading soils on Earth, and results were even more promising than with the Martian regolith, where intercropping led to a significant increase in yield for 2 out of the 3 species present, and gave an overall significant advantageous performance compared to the species monocropping counterparts. These results contribute to collective progress of intercropping research to tackle global matters.

Gonçalves emphasised, "I believe that this type of research holds extraordinary potential for providing out-of-the-box solutions that can significantly contribute to our joint efforts of tackling climate change and ensuring food security for people worldwide, especially if we can add to the ongoing efforts of intercropping research on these issues. Whatever we learn from farming on Mars can be practically and directly translated to farming on Earth. 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 two problems with a single strike.”