Physicochemical Characterization and Stability of Biochar Obtained from 5 Species of Forest Biomass in Peru

The maintenance of the extensive parks at National Agrarian La Molina University (UNALM) generates a large amount of forest biomass, with high treatment costs. For this reason, the pyrolysis of the forest biomass is an alternative for valorization, allowing proper management producing biochar. The aim of the research was to evaluate the stability of biochar at 300°C and 500°C from forest biomass of five predominant species at UNALM, Grevillea robusta, Schinus molle, Casuarina cunninghamiana, Ficus benjamina and Eucalyptus spp. To determine the stability of biochar produced, two methodologies were used (IBI and an adaptation of the López et al.(2010) method), for which organic, labile, oxidizable, recalcitrant carbon on biochar were determined. The results showed a decrease in biochar yield of 6.50% with an increasing pyrolysis temperature. Regarding physicochemical characteristics, the biochar produced was alkaline (pH above 8); besides, the pH and electrical conductivity increased with temperature, by 0.64 and 0.38 ds/m, respectively. However, in the case of nitrogen and ashes, the opposite occurred. It was concluded that all the biochar produced complied with the stability limits according to the applied methodologies, and BSM500 had the highest value of stability considering the applied methodologies. This may indicate that it could have the greatest sequestration of C once applied to the soil and also the reduction of emissions; for that reason, it would be important to carry out future research to estimate the potential for C sequestration in the long term.