Managing Global Resources for a Secure Future

Vanessa Barreto, Kristina Hatakka and Yuch Ping Hsieh

It is known for some time that turning biomass into a “char” form could considerably reduce its bio-degradation rate in soils and thus provide a powerful means to sequester carbon. Quantitative information of the biochar biodegradation in soils, however, is limited, especially with reference to the property of a biochar. This study was initiated to investigate the mean residence time (MRT) of biochar in soil produced from switchgrass (Panicum virgatum) under temperatures of 400 oC and 600 oC, respectively. We used the naturally distinct 13C signatures between the char and the soil to trace the decomposition of biochar in soil and relate the decomposition rate to the thermochemical property of the char. The results showed that the MRT of the char increased at least 100 times when compared with the un-charred grass. Although the 600 oC char has longer MRT than that of the 400 oC char, the extra cost and energy needed to produce the 600 oC char may offset its benefit in carbon sequestration. Multi-element scanning thermal analysis of the char indicated that the degree of carbon