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Saman Herath Mudiyanselage

Doctor of Philosophy, (Soil science)
Study Completed: 2013
College of Sciences


Thesis Title
Stability of Biochar and its Influence on the Dynamics of Soil Properties

Mr. Herath studied the stability of biochar and its influence on the dynamics of soil properties in organic carbon-rich soils (an Alfisol and an Andisol). Key findings suggest that the biochars have positive effects on the improvement of soil physical properties (mainly the hydraulic properties). Soil incubation data in conjunction with modelling suggest that the biochars tested will remain in soil at least for centennial time periods, and may protect native soil organic matter from microbial degradation. When physically-fractionating the biochar-amended soils, biochars were found to be mainly concentrated into the so-called “unprotected soil organic carbon pool”, which is conceptually defined as labile. The implications of the findings are the following: (i) the biochars tested tend to increase the resilience of the plant-soil system during a dry spell and reduce the irrigation frequency; (ii) the study provides a solid base regarding the longevity of biochar-C in these soils; and (iii) the biochars under study contribute to carbon sequestration by avoidance of CO2 emission from feedstock and enhanced protection of native organic matter; this effect is more evident in the presence of plants. Finally, this study proposes a modified fractionation methodology for the “unprotected soil carbon pool” using dichromate oxidation in order to distinguish the biochemically protected fraction (recalcitrant) from the true labile carbon of this pool.

Professor Marta Camps Arbestain
Professor Michael Hedley