Soil aggregates are the basic unit of soil structure, consisting of primary particles (sand, silt and clay), inorganic cements, organic material at different stages of decay and living organisms, all bound together in clusters of different order of magnitude in a multi-scale manner. There is a strong relation between all components of soil aggregates from the micro to macro scale. For instance, a reduction in soil organic matter may result in the long-term degradation of soil structure due to a decrease in the ameliorative action of soil microorganisms causing a reduction in A horizon, reduced range, size and complexity of pores, promoting the formation of finer and weaker aggregates. These traits are associated with soils susceptible to physical degradation i.e. surface crusting, compaction, and erosion resulting in soil losses, poor crop establishment and eventually yield.

The soil physical environment determines the chemical and biological properties of soil and vice-versa. The study of aggregate formation and stability has received great attention in the last few decades, typically associated with soil organic matter. Nowadays, with the availability of sophisticated equipment (X-ray Computed Tomography, rheology, mechanical precision stress inducer etc.) allowing the investigation of the intact aggregate pore structure and networks, the strength and degree of degradation, we are able to improve our understanding of soil aggregate formation and stability as it is a dynamic and complex process.

The aim of this session is to focus on the concept of soil aggregation in a multi-scale, multi-temporal and multi-spatial manner which is essential for making improvements in agriculture as it is related to soil-root interactions, hydrological properties and environmental issues. Contributions to this session are welcomed and encouraged from researchers focusing on aggregate formation, aggregate stability, modeling, and either theoretical or practical concepts of soil aggregation.