Soil microbes to mitigate climate change

Human populations are expected to increase by 50% to 9 billion by 2050 as climate change continues - together these changes will place unprecedented pressure on the Earth's finite and fragile natural resources. There is growing social, economic and political concern about the impacts of climate and land use change on global biodiversity and the goods that the environment supplies. A key challenge is to manage terrestrial ecosystems sustainably whilst mitigating climate change. An immediate opportunity is to reverse global soil organic carbon (SOC) losses, and increase soil carbon stocks by 0.4% per year, articulated as the proposed '4 per mille' target (launched at COP21, 2015, www.4p1000.org). This global initiative could halt the rise in atmospheric CO2 concentrations. However, identifying land management strategies to 'lock up' CO2 in soil is hampered by poor understanding of SOC stabilisation. Recent evidence shows that carbon compounds produced by microbes form the majority (50-80%) of SOC with the remainder derived from plant inputs (Sokol et al. 2018; Keiluweit et al 2015). Yet, the biophysical and chemical mechanisms determining the stabilisation and long-term persistence of SOC are highly uncertain (Liang et al. 2017).

PhD project research will focus on the potential to manage soil microbial communities as a means to sequester atmospheric CO2 in the soil, to achieve the 0.4% target. The project will investigate mineralogical and microbial processes that transform and stabilize soil organic carbon using an experimental approach combining 'state-of-the-art' biogeochemical and stable isotope techniques to address the following research question:

How do microbial and mineralogical mechanisms together determine the stabilization and long-term persistence of soil organic carbon?

An experimental approach combining 'state-of-the-art biogeochemical and stable isotope techniques will be used to answer the following specific research questions:

Q1. How does the composition of organo-mineral complexes influence their resilience to microbial degradation?
Q2. How does soil mineralogy influence microbial transformation and stabilization of plant inputs?
The student will be supported in designing microcosm and mesocosm experiments to address these research questions and gain a novel mechanistic understanding of the abiotic and biotic pathways of SOC stabilization.