Solicited speaker: Dr Marco Keiluweit
Reduction and oxidation (redox) reactions are crucial for many chemical and biological processes occurring in the soil. The redox condition measured by its potential together with the pH determines which reactions are possible. Redox conditions are major drivers for, among others, microbe-induced organic contaminant degradation, protection of organic archaeological artifacts under wet conditions, and emissions of greenhouse gases.
Nevertheless, monitoring is a challenge and multiple techniques exist. Moreover, modelling redox reactions can be a complicated task because chemical, physical and biological processes are involved.
Soil minerals, and especially finely divided soil minerals (e.g. phyllosilicates, metallic oxides and hydroxides, allophanes…), deeply influence soil functioning. Due to their large and reactive surfaces they can adsorb organic molecules, nutrients or metals, strongly affect soil microstructure and pore system and are involved in aggregate formation and dynamics. As a result soil mineralogy is of primary importance regarding key soil services such as soil carbon sequestration, soil fertility or pollutant retention. However, much remains to be investigated to improve our understanding of the importance of mineralogy on soil functioning.
Soil aggregation is essential to ensure soil quality and avoid degradation, since the formation of stable aggregates increases water retention and infiltration, aeration, microbial activity, movement of fauna, reduces erosion rates, and facilitates the development of vegetation. It is known that the stabilisation of organic carbon (C) in soil aggregates is one of the main mechanisms for long-term C storage in soils. However, the genesis and dynamics of microaggregates and macroaggregates is still controversial, with different models and hypotheses dealing with C stabilisation within different aggregate fractions and how these fractions are formed.
These three properties –redox state, mineralogy, aggregation- have tremendous impacts on soil functioning. In this session, we aim to bring together experimentalists and modelers from different disciplines (among others soil science, wetland science, hydrology and microbiology), working on these properties and aiming at better understanding their influence on soil structure, soil reclamation, carbon and nutrient dynamics, microbial activity, soil organic matter stabilization and organo-mineral interactions. Contributions using new monitoring or modelling approaches, combining measurements and modelling, and addressing scale issues are most welcomed. We encourage multi-disciplinary contributions that integrate soil knowledge with management practices associated to different soil types, land uses and climates.