Martian regolith is very different from Earth soil. In order to colonize, or have an extended stay on Mars, agriculture must be established. The purpose of this experiment was to investigate growing plants in Martian regolith in a manner that would be fuel-efficient, by using the existing soil of Mars with minimal interference and minimal materials brought from Earth. The regolith used was Mojave Mars Simulant-2 (MMS-2), developed by The Martian Garden. MMS-2 is more than a 90% match to the chemical composition of the regolith on Mars. Plant growth was compared between Earth soil (control), 50% Martian regolith MMS-2/50% Earth soil mixture (Mars Mix A), and 50% Mars regolith MMS-2/25% coffee grounds/12.5% Earth soil/12.5% vermiculite mixture (Mars Mix B). Plants were grown in all three mixtures and growth was measured during three month cycles. Although several plant species were planted, only kale produced any significant measurable data. Plant growth decreased with decreased percentages of Earth compost additive as measured by plant length and robustness. Efforts to reduce the mass of additives required to support plant growth include an exploration of acidifying Martian regolith MMS-2 prior to planting. Acids have been chosen for their ability to add critical nutrients of nitrogen and phosphorus. Nitric acid and phosphoric acid have both effectively lowered the pH to 6, similar to the optimal pH range for plant growth. The implications of this study indicate that Martian regolith and Earth soils on their own will not be sufficient to begin agriculture on Mars. Further research on chemical soil amendments will be needed for sustainable agricultural development on Mars.

Growing sustainable crops on Mars is an important aspect of developing a colony on the red planet. The goal of this research is to modify Martian regolith simulant to support plant growth. Results will be presented for the readjustment of the pH of Mars soil (pH 8) simulant to match that of typical fertile earth soil (pH 6) using nitric and phosphoric acid. The acids used were chosen based on their viability for transport to Mars and their ability to add crucial nutrients for plant growth in the unfertile soil. During the project, both acids effectively lowered the regolith pH, but in the hours and days following the pH increased significantly, which has motivated testing the buffer capacity of Mars soil simulant. The data collected was used to prepare three samples of Mars soil simulant; the first was modified with phosphoric acid, the second with nitric acid, and the third was also modified with nitric acid and had a buffer of dihydrogen phosphate added. The growth of kale was measured in the three modified soils, each mixed with equal parts potting soil. Kale growth was compared to trials performed without the acidification or buffering of Mars simulant soil.  Our research presents progress towards growing food in Mars regolith to sustain colonization efforts on the planet. This work can also be applied to the potential need to grow food in adverse conditions on Earth as the human population increases and the impacts of climate change advance.