Assessing the Potential of Biomass Hydrothermal Liquefaction Hydrochar for Soil Amendment: Chemical/Physical Characterization and Water Holding Capacity and Retention

Extensive research has been conducted on the application of pyrolysis and hydrothermal carbonization (HTC) biochar for soil amendment. However, hydrochar from hydrothermal liquefaction (HTL) has received little attention regarding its potential for such application. This research paper aims to fill this knowledge gap. In this study, corn stover-derived hydrochar from HTL at 280 °C was characterized using suitable analytical techniques to determine the functional groups, specific surface area, and morphology. The effects of HTL hydrochar on water holding capacity (WHC) and water retention of sandy loam soil and the resistance to biodegradation were also studied. The BET surface area of hydrochar was found to be 27.6 m2/g. The hydrochar particles are micro-sized stacking of nanometer-thick foliates. The hydrochar-amended soil consistently showed better WHC ranging from 50 to 55% compared to the unamended soil of 48%. A similar trend was observed for water retention over a period of four days. No notable biodegradation was observed for the hydrochar over a period of 106 days in wet soil at the ambient temperature. Overall, these results demonstrate the potential of HTL hydrochar as a valuable soil amendment to enhance agriculture sustainability.