Root-Pore Interactions and Soil Fauna: Investigating Carbon Fate during the Decomposition of Roots in Structured Soil (ROOT-DECAY)

• Applicant: Dr. Maik Geers-Lucas
• Subject Area: Soil Sciences
• Term: since 2026
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 572736872

As plant roots grow, they navigate through various structures, such as biopores, cracks, and the dense soil matrix, creating diverse microhabitats in the rhizosphere that potentially influence carbon dynamics. While, microbial activity is primarily restricted to water-filled pores of a few micrometers, meso- and macrofauna are mainly found in air-filled pores that match their body size. Since different root systems utilise the existing macropore system to different extents, different microhabitats can be expected along the root system of different plants. However, the effects of changing local habitat characteristics along the root on its later degradation and resulting carbon fate are largely unexplored. The objectives of this project are to: 1) investigate how root–pore interactions differ among plant species in response to microenvironmental cues, 2) assess how these interactions affect the accessibility of root litter to soil organisms, particularly mesofauna, and 3) examine how these processes influence the formation of soil organic matter fractions, including particulate organic matter (POM) and mineral-associated organic matter (MAOM). To achieve these objectives, the project will combine controlled laboratory and field experiments, comparing plant species with contrasting root systems—barley, sorghum, and faba bean. We will use X-ray computed tomography (CT) to generate high-resolution images of root growth and link them to key environmental factors such as soil structure, oxygen availability (O₂), and mechanical impedance, and monitor the breakdown of roots by soil fauna. Stable isotope labeling with ¹³C will be used to trace the flow of root-derived carbon into different fractions of soil organic matter and into soil fauna. Understanding root-pore interactions and their effects on carbon fate in soil will provide crucial insights into ecological and biogeochemical processes that determine soil organic matter formation and storage, and thus shape terrestrial ecosystems. This knowledge can inform sustainable soil management practices and improve predictions of carbon cycling in terrestrial ecosystems.

• DFG Programme: Research Grants