Enhancing Extraterrestrial Regolith Based Agriculture using Microbial Symbioses and In Situ Nutrient Sources

Long-term human presence on the Moon and Mars requires sustainable, resource-efficient food production systems. Regolith-based agriculture (RBA) utilizes planetary regolith (mineral, inorganic soils) as a growth substrate capable of providing nutrients for extraterrestrial agriculture. Previous experiments indicate plants grown in Apollo-returned and simulated lunar and martian regolith suffer stress from nutrient limitation and metal toxicity. Arbuscular mycorrhizal fungi (AMF) form symbioses with most crops and have the ability to significantly reduce these stresses by delivering nutrients and water previously unavailable to a plant, as well as aiding in phytoremediation of contaminants and toxins. Legumes form symbioses with both nodule-forming nitrogen (N) fixing bacteria and AMF. Since lunar and martian simulated regolith lack bioavailable N, its supplementation, through bacterial symbiosis, for legumes, or fertilizer for other crops, is essential for plant survival and biomass production. Our experiments test the influence of AMF on five crops grown in simulated lunar and martian regolith, measuring survival and biomass production for all crops, and comparing yield between urea-derived N and biosolid (derived from human wastewater) fertilizer in maize. All crops successfully grew in both regoliths. Mycorrhizal inoculation produced crop-specific improvements in performance metrics; some crops showed enhanced biomass production while others exhibited improved nodulation or leaf health. Biosolid fertilization consistently surpassed urea N in maize, exhibiting increased biomass, yield of produce, leaf chlorophyll content, and some tissue nutrients in lunar regolith. AM fungi and bioregenerative fertilizers enhance regolith-based crop vitality, offering a potential pathway toward agricultural self-sufficiency on the Moon and Mars.