Agriculture on Mars: study reveals challenges and possible solutions

The study used small pots in a controlled greenhouse environment to grow peas (Pisum sativum), carrots (Daucus carota) and tomatoes (Solanum lycopersicum) in three types of soil

06.05.2024 | 16:45 (UTC -3)
Cultivar Magazine
Comparison between the combined treatment of the three soils: (A) sand; (B) Mars regolith simulator; (c) potting soil.
Comparison between the combined treatment of the three soils: (A) sand; (B) Mars regolith simulator; (c) potting soil.

Researchers have been investigating advanced agricultural techniques for future colonies on Mars, focusing on local production of fresh foods. One prominent technique, the intercropping system, was studied in a simulated environment using soil types that mimic Martian conditions. This study provides new insights into how to optimize resource use under extreme conditions.

The study used small pots in a controlled greenhouse environment to grow peas (Pisum sativum), carrots (Daucus carota) and tomatoes (Solanum lycopersicum) in three types of soil: a Martian regolith simulant (MMS-1), potting soil, and sand. Planting techniques have included both monoculture and intercropping, where multiple species are planted together.

Key Findings

Intercropped planting was shown to be beneficial for the growth of tomatoes but detrimental for peas and carrots in simulated Martian soil, resulting in an overall yield disadvantage compared to monoculture. The absence of nodule formation on the pea roots, essential for nitrogen fixation, was a significant factor, as they were unable to benefit from its complementary properties.

The Mars simulated soil presented challenges due to its high compaction and high pH, ​​limiting the survival and nodulation of Rhizobia bacteria, crucial for nitrogen fixation. In contrast, sand, with more favorable conditions, allowed effective nodulation and superior intercropping performance.

To improve growing conditions on Mars, researchers suggest tweaks to the regolith, such as selecting a larger grain to reduce compaction and adding organic matter, such as composting crop residue, to enrich the soil. Future studies will focus on integrating all factors involved, including the toxicity of certain compounds present on Mars, aiming to develop a robust and efficient agricultural system for future colonies.

See the researchers' summary of the article:

Future colonists on Mars will need to produce fresh food locally to acquire essential nutrients lost in food dehydration, the main technique for sending food into space. In this study we intend to test the feasibility and perspective of applying a consortium system as a method of producing food in soil in Martian colonies. This new approach to Martian agriculture adds valuable information about how we can optimize resource utilization and improve colony self-sustainability, as Martian colonies will operate with very limited space, energy and terrestrial supplies.

A likely primitive agricultural scenario on Mars was simulated using small pots, a controlled greenhouse environment, and species conforming to space mission requirements. Pea (Pisum sativum), carrot (Daucus carota) and tomato (Solanum lycopersicum) were cultivated in three types of soil (mars regolith simulator “MMS-1”, potting soil and sand), planted mixed (intercropping) or separately (monoculture). Bacteria Rhizobia (Rhizobium leguminosarum) were added as a pea symbiont for nitrogen fixation. Plant performance was measured as above-ground biomass (g), yield (g), harvest index (%) and nitrogen/phosphorus/potassium content in yield (g/kg). The overall performance of the consortium system was calculated as relative total yield (RYT).

Intercropping had clear effects on plant performance in Martian regolith, being beneficial for tomatoes but mainly detrimental for peas and carrots, ultimately giving an overall disadvantage in yield compared to monoculture (RYT = 0,93 ,1,32). This effect likely resulted from the observed absence of rhizobial nodulation in the Martian regolith, denying nitrogen fixation and preventing intercropped plants from taking advantage of their complementarity. Adverse regolith conditions - high pH, ​​high compaction, and nutrient deficiencies - presumably restricted rhizobial survival/nodulation. In sand, where more favorable soil conditions promoted effective nodulation, intercropping significantly outperformed monoculture (RYT = XNUMX).

Given this, we suggest that, with simple improvements in the regolith, improving nodulation conditions, intercropping shows promise as a method to optimize food production in Martian colonies. Specific regolith improvements are proposed for future research.

The full article can be read at doi.org/10.1371/journal.pone.0302149

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