Roles of Biochar in the Rehabilitation of Degraded Lands
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Intensive agricultural practices and increasing mining activities, driven by increasing world pollution and rapid economic development in the past decades, have resulted in a significant increase in degraded lands on a global scale. The key features of these degraded lands include high availability of heavy metals, low concentrations of organic matter and nutrients [e.g. nitrogen (N)], high alkalinity, salinity and sodicity, high acidity, soil erosion and soil structural decline. One of examples is the increasing deposition of bauxite-processing residue from bauxite ore refineries, with the current global storage of bauxite residue of about 3 Gt and the estimated annual world production of bauxite-processing residue of 120 Mt. The rehabilitation of bauxite residue storage areas is essentially required but frequently retarded by the hostile conditions such as high alkalinity and sodicity, low fertility and high hydraulic conductivity. To deal with these environmental issues, effective mitigation and remediation strategies are needed. One of remediation options is the amendment of different organic (biosolids, composts, biochars etc.) and inorganic materials (lime, fertilizers etc.) to improve soil chemical, physical and biological properties in degraded lands. Biochar, as a carbon-rich material, can be produced under pyrolytic conditions, wildfires or prescribed burning for fire management. Biochars have long-term stability and are considered to be able to improve soil health and plant productivity by reducing concentrations of available heavy metals and increasing nutrient (e.g. N) and water retention. However, properties of biochars vary with their feedstock materials and production (e.g. pyrolysis) conditions. Consequently the effectiveness of biochar amendments is different as a result of interactions of different biochar’s properties and soil properties.
Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
Griffith School of Environment
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