Farming on Mars sounds like science fiction, but it’s a very real problem that scientists must solve for long-term human colonization. Of the top five commodities needed for a Mars settlement—energy, oxygen, materials, water, and food—food is the only one not naturally available on the Red Planet. The main challenge is the “soil,” a dusty, rocky material called regolith. Martian regolith is essentially weathered rock with almost no carbon; it’s terrible for farming because it has extremely poor water retention. Like sand, water poured onto it just seeps away, making agriculture incredibly inefficient. A new study in the Journal of Analytical and Applied PyrolysisPyrolysis is a thermochemical process that converts waste biomass into bio-char, bio-oil, and pyro-gas. It offers significant advantages in waste valorization, turning low-value materials into economically valuable resources. Its versatility allows for tailored products based on operational conditions, presenting itself as a cost-effective and efficient More by Robert W. Cheatham, Al Ibtida Sultana, and M. Toufiq Reza details a promising breakthrough: a new method to “co-activate” this regolith, transforming it into a material that can hold the water future crops will need.

The team’s solution was to amend the Martian regolith with hydrochar, made from Loblolly pine. On Earth, adding biocharBiochar is a carbon-rich material created from biomass decomposition in low-oxygen conditions. It has important applications in environmental remediation, soil improvement, agriculture, carbon sequestration, energy storage, and sustainable materials, promoting efficiency and reducing waste in various contexts while addressing climate change challenges. More to soil is a known way to improve its quality. The researchers, however, went a step further. They didn’t just mix the two. They created a novel composite material by mixing Martian regolith (MR) with hydrochar (H) in various ratios, from 5% hydrochar (H5-M95) to 50% hydrochar (H50-M50). Then, they “co-activated” this mixture using potassium hydroxide (KOH) and high heat (800°C). This chemical process impregnates the hydrochar and, after washing, leaves behind an intricate network of microscopic pores, fundamentally changing the material’s structure.

The results for Water Holding Capacity (WHC)—the soil’s ability to hold water against gravity for plants to use—were dramatic. The untreated Martian regolith, as expected, had a very low WHC of about 30%. Pure hydrochar alone was better, but not by much, at about 53%. The co-activated composites, however, were a different story. The sample with just 5% hydrochar and 95% regolith (H5-M95) achieved a WHC of 96.2%. This simple 5% addition more than tripled the regolith’s ability to store water, making it far superior to either of its starting components and bringing it in line with viable agricultural soil.

This impressive jump in water storage is thanks to a massive increase in porosityPorosity of biochar is a key factor in its effectiveness as a soil amendment and its ability to retain water and nutrients. Biochar’s porosity is influenced by feedstock type and pyrolysis temperature, and it plays a crucial role in microbial activity and overall soil health. Biochar More. The activation process works like a chemical drill, etching tiny pores and channels into the material. The team found that adding more hydrochar created more pores; the 50% hydrochar mix (H50-M50) had a 287% greater specific surface area than the lower-ratio mixes. This vast, new internal “spongy” structure, along with a 211% boost in carbon content for the 50% mix, is what traps the water. While the 50% mix was the most porous, the 5% mix hit the sweet spot for holding water. This sample (H5-M95) also showed minimal water loss over 24 hours, losing only about 4%—a huge improvement for an environment where every drop of water is precious.

This research is a key step in in-situ resource utilization, or using materials already present on Mars to build a sustainable habitat. It proves that Martian regolith isn’t just useless dust; it’s a raw material that can be engineered. By processing a relatively small amount of biomassBiomass is a complex biological organic or non-organic solid product derived from living or recently living organism and available naturally. Various types of wastes such as animal manure, waste paper, sludge and many industrial wastes are also treated as biomass because like natural biomass these More (like pine, which could be grown in early biodomes) with the abundant regolith, future colonists could create their own viable farmland. This ability to “activate” the ground beneath their feet is a practical and efficient solution, bringing us one step closer to growing green on the Red Planet.

Source: Cheatham, R. W., Sultana, A. I., & Reza, M. T. (2025). Co-activation of Martian regolith and hydrochar for enhanced water retention and water holding capacity. Journal of Analytical and Applied Pyrolysis, 189, 107064.