There is increasing pressure from the community, business and government to increase the storage of carbon in farming soils (eg. 4 per mille initiative) to offset human-made emissions. But can this be realistically achieved, and do we (the science community and farmers alike) have a sound understanding of how to do this? The genesis of soil organic carbon (SOC), as organic matter, is a complex interplay between inputs, and stabilization and/or priming of new and existing soil organic matter, and physical losses (leaching, erosion). The traditional understanding for ‘new’ C preservation as SOC is through; selective preservation which favours more molecularly diverse organic matter; via spatial inaccessibility where the occlusion or incorporation of C within aggregates or phytoliths protect it from microbial mineralization, and protection via organo-mineral and organo-organic interfaces.
Lukas will discuss new data that critically interrogates our current knowledge of organic matter protection and turnover mechanisms. He will discuss the role of fire, pyrolysis and charcoal (biochar) in building SOC, and importantly, the role of iron (Fe) minerals and how the ‘rusty sink’ may be manipulated to control C turnover processes. Fe-mediated SOC protection, ie. by Fe oxides, (hydr)oxides and (oxy)hydroxides) has traditionally been recognised as occurring via adsorption, co-precipitation or aggregation processes. However, the electron transfer during the cycling between Fe(II) and Fe(III) influences both sequestration and mineralization processes, and opportunities exist to further understand and exploit these mechanisms. Importantly, an understanding of both edaphic controls and keystone microbiota that drive these processes is generally lacking and will be examined.
Finally, Lukas will describe some strategies and mechanisms for fostering the genesis of soil organic matter to deliver productive, fertile Anthrosols from soils that currently have a low SOC storage ceiling.
Lukas completed a PhD at the University of Sydney in 1995, and then joined the New South Wales Department of Primary Industries (a State Government Department in Australia) where he is now a Senior Principal Research Scientist. He is a Program Leader in the Soil Cooperative Research Centre and Adjunct Professor at Griffith University and Southern Cross University. His research focus includes C and N cycling, and how this relates to soil carbon storage (for climate mitigation/ adaptation, productivity and resilience), unravelling soil rhizosphere and microbial processes. He is a Highly Cited Researcher (2018-2020) with over 200 published papers, including works in Nature Climate Change and Nature Communications