Extensive research has investigated biochar from pyrolysis and hydrothermal carbonization (HTC) for soil amendment, yet hydrochar produced via hydrothermal liquefaction (HTL) has received limited attention. This study addresses this gap by evaluating the potential of HTL hydrochar, derived from corn stover at 280°C, as a soil amendment to enhance agricultural sustainability. The hydrochar was characterized using advanced analytical techniques to examine its functional groups, morphology, and specific surface area. Results revealed a BET surface area of 27.6 m²/g, with particles forming micro-sized stacks of nanometer-thick foliates, indicating a unique structural composition suitable for soil applications.When applied to sandy loam soil, the HTL hydrochar significantly improved water holding capacity (WHC), achieving 50–55% compared to 48% in unamended soil. This enhancement was consistent, with improved water retention observed over a four-day period, suggesting its potential to support crops in water-scarce environments. Additionally, the hydrochar demonstrated remarkable resistance to biodegradation, showing no significant degradation over 106 days in moist soil at ambient temperature. This stability enhances its long-term efficacy as a soil amendment.These findings highlight HTL hydrochar’s underexplored benefits, including improved soil water management and support for sustainable agricultural practices. By addressing the research gap on HTL hydrochar, this study underscores its potential to contribute to ecohydrology and agricultural water systems, offering a sustainable solution for enhancing soil health, water retention, and crop productivity in farming systems facing environmental challenges. Further research could expand its applications in diverse soil types and climates.