Soils contain the largest dynamic reservoir of carbon on Earth - larger than that stored in the atmosphere and vegetation combined. This makes soils a critical component of the global carbon cycle. Soil carbon (C) is mostly bound in what we call “soil organic matter”, or SOM—although carbonate (CO3) minerals also contribute to soil C storage. SOM is composed of dead biomass (detritus) from roots, plant litter, animals, and microorganisms, plus live microorganisms that actively consume and produce a diverse mixture of C-containing compounds. Carbon is lost from soils as a result of this microbial decomposition of SOM, which eventually leads to the emission of greenhouse gases (carbon dioxide and methane) or C leaching with groundwater to surface water. The amount of C stored in soils is the balance between detritus input and export of gases and dissolved C from the soil. There are multiple factors controlling the rate of microbial decomposition and thus export of C from the soil, for example the association of SOM with soil minerals, protection within soil aggregates, and environmental conditions that influence the metabolic activity of microorganisms.
Through field, lab and modeling-based experiments, our group aims to explain the underlying mechanisms controlling the storage and movement of carbon in soil. We focus on:
● the functional differences, and resulting rates, in microbial communities responsible for soil carbon decomposition;
● the effects of climate change and management practices on the fate of soil carbon, and fluxes between atmosphere and soil;
● mechanisms controlling resistance of SOM to breakdown and release (e.g. oxygen limitation and molecular composition of SOM); and
● the role of soil carbon in contaminant retention and release to waterways.