Studying the role of biochar using isotopic tracing techniques

Abstract

Several names are used for materials produced by pyrolysis such as pyrogenic carbon, black carbon, char(coal), biochar, pyrochar or plant char (Schmidt and Noack 2000, Glaser et al. 2002, Lehmann 2007, Bird and Ascough 2011, Knicker 2011). There are two major problems related to this variety of names. First, material derived from pyrolysis is not a defined substance, instead material properties depend on the production process, temperature and duration which is better expressed by a combustion continuum or by elemental ratios such as O/C and H/C (Fig. 1). There is still no common definition for this type of materials. Second, pyrolysis products are important across a range of disciplines such as material science, natural sciences including soil science, chemistry and biology, and agronomy each of which has an own terminology and a set of methodologies for the analysis of this material and interpretation of results. The term biochar was first used by Karaosmanoglu et al. (2000) for pyrogenic carbon produced on purpose by humans under controlled pyrolysis conditions in order to generate (i) gases for power generation (syngas), (ii) a range of bio-oils and (iii) biochar for soil amelioration in agriculture and for carbon sequestration.