Regional Considerations for Targeted Use of Biochar in Agriculture and Remediation in Australia

This chapter provides an overview of biochar research within Australia with particular consideration given to the importance of regional land-use diversity in defining both the dominant feedstock materials used and the dominant target systems and associated productivity constraints or remediation requirements. A large proportion Australian biochar research has focused on quantifying the contribution of biochar to long-term carbon sequestration and to manage soil N2O emissions, with secondary aims of determining the impact on plant productivity. The data continues to underpin policy development, with recent findings highlighting the importance of biochar-mineral interactions in determining the fate and persistence of biochar in Australian soil systems. The use of biochar as a soil amendment generally reflects that of the wider global literature, showing greater potential for improved productivity in highly weather acidic soils (e.g. Ferrasols) compared to other soil types (e.g. Vertosols, Tenosols, Calaresols). The likely mechanisms relate to direct pH amelioration and associated changes in nutrient availability (N, P) and toxicity (Al). Wider discussions include improving buffering and cation exchange capacity to address risks of acidification and N leaching in the coarse textured soils of the West, and the yet unexplored potential to improve the competitive advantage of legume rotations in acidic soils of the Southern region. The risk of reduced herbicide efficacy continues to cause concern, however field scale assessment is lacking. A growing understanding of the sorptive and reactive characteristics of biochar supports the development of more targeted and integrated use of biochar for agricultural and environmental management. This includes the incorporation of biochar into mineral and organic fertiliser products with slow release characteristics, the rehabilitation of bauxite mining sites, and the use of biochar within a whole of systems approach aimed at managing acid sulphate soils. The meaningful development and use of biochar is intrinsically linked to establishment of a bioenergy industry, which in Australia continues to be fragmented and contributes only a small proportion of energy. Consequently research, development, and adoption of biochar in agriculture and environmental management suffers the supply and demand issues common to any emerging industry.