Rhizodeposit conditioning of lunar regolith into arable soil for sustainable space agriculture

Overview

This research proposes a biological method for converting lunar regolith into arable soil by conditioning it with plant root rhizodeposits. The approach uses root exudates—sugars, organic acids, and phenolics—to directly improve soil organic carbon, available nutrients, and water retention, while indirectly enhancing plant biomass over successive growth cycles. By sequentially growing maize plants in lunar regolith, rhizodeposits accumulate to improve water retention and soil aggregate stability over time. This innovation addresses one of the most critical challenges for long-duration space missions: producing food in situ without transporting large quantities of Earth soil.

The technology has direct applications for space agriculture, lunar habitat sustainability, and closed-loop life support systems. It also offers potential terrestrial benefits for soil rehabilitation in degraded or resource-limited environments.

Technical specifications

Key features:

• Uses maize as a priming crop due to its large root diameter and high exudate output, ideal for rhizodeposit studies
• Targets three functional groups of root exudates: sugars, organic acids, and phenolics
• Employs sequential planting cycles (10 sequential plantings until four leaves emerge) to progressively build soil organic matter
• Analyzes exudates and pore water via LC-MS at V1 and V4 growth stages to identify optimal conditioning phases
• Measures water retention, aggregate stability, and pore size distribution using a novel ultrasonic soil imager
• Leverages stressed plant exudation: stressed plants continue or increase exudate production, enhancing conditioning effects
• Validates micropore water holding capacity improvements through moisture-dependent x-ray diffraction

How it works:

Root exudates interact with regolith mineralogy at the pore scale, improving hydrology and stabilizing soil aggregates. Initial conditioning with phenolics, organic acids, and glucose enhances micropore water retention. Subsequent maize growth cycles deposit additional rhizodeposits, building organic carbon and improving soil structure over time.

Technology readiness level

This research is at an early-to-mid stage of development (TRL 2–3). Preliminary lab data demonstrates that adding phenolics, organic acids, and glucose improves water holding capacity in terrestrial soil as measured by moisture-dependent x-ray diffraction. Supporting evidence shows that maize exudation profiles shift across early development stages, and that stressed plants maintain or increase exudate output. The approach has not yet been tested in actual lunar regolith, though scientific literature supports the underlying mineralogy–rhizodeposit interactions. Future validation will involve growing maize in regolith over 10 sequential plantings, with comprehensive chemical and structural analyses before and after conditioning. The team seeks support for regolith and exudate provision and funding for analytical services.