Improving Carbon Sequestration of Biochar through Biomass Chemical Modification

Abstract

Wei Zheng - Senior Research Scientist/Adjunct Faculty at the Illinois Sustaianble Technology Center, a division of the Prairie Research Institute at the University of Illinois at Urbana-Champaign.

Biochar is being actively explored as a tool for long-term carbon sequestration in soil. In this study, several P-containing substances were added into biomass to produce modified biochars. We found that the TSP chemical fertilizer as an additive could significantly increase carbon retention during biochar production. Compared to unmodified biochar with 50% carbon content, more than 75% carbon would remain in the modified biochar generated from switchgrass mixed with TSP. The thermo-gravimetric analysis showed that the oxidative stability of the modified biochar was significantly enhanced, suggesting that it is very recalcitrant to chemical degradation. A soil incubation experiment was conducted to determine biochar microbial stability in soil. The emissions of CO2 from the soils amended with the modified and unmodified biochars were very little with no discernible difference. These results indicate that both biochars are stable in soils and the TSP additive has no effects on biochar decomposition.