Soil Aggregation and Microbial Interactions

Soil aggregation is the process by which individual mineral particles and organic matter coalesce into larger, stable units that shape pore architecture, water retention and resistance to erosion. Microbial communities drive much of this aggregation through the production of extracellular polymeric substances (EPS), hyphal networks and biofilm formation. These biotic agents bind mineral grains, enmesh organic residues and modify aggregate surfaces, thereby influencing the formation, stabilization and turnover of microaggregates (<0.25 mm) and macroaggregates (≥0.25 mm). Root exudates further stimulate microbial activity and selectively enrich fungal and bacterial taxa that promote aggregate formation in both topsoil and subsoil horizons. Physicochemical factors such as clay content, cation exchange capacity and pH interact with microbial processes to determine aggregate stability, while land-use history and management practices modulate the availability of labile carbon substrates. Together, these biotic–abiotic interactions underpin soil structure, carbon sequestration and nutrient cycling at local and global scales. Understanding the mechanisms by which microbes engineer soil architecture is therefore essential to predict responses to climate change, optimise agricultural productivity and safeguard ecosystem services.

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Soil Aggregation and Microbial Interactions publication trend

The graph below shows the total number of articles in soil aggregation and microbial interactions across all publications each year (not limited to Nature Index journals).

Technical terms

Soil aggregate: a cluster of mineral particles and organic matter bound by biotic and abiotic agents.

Macroaggregate: a soil aggregate larger than 0.25 mm, contributing to macroporosity and rapid water transport.

Microaggregate: a soil aggregate smaller than 0.25 mm, often nested within macroaggregates and important for long-term carbon protection.

Extracellular polymeric substances (EPS): hydrated polysaccharides, proteins and nucleic acids secreted by microbes that glue soil particles together.

References

1. Effect of pre-treatment processes of organic residues on soil aggregates. Environmental Technology & Innovation (2023).
2. Microbial Extracellular Polymeric Substances: Ecological Function and Impact on Soil Aggregation. Frontiers in Microbiology (2018).
3. Root Exudates Induce Soil Macroaggregation Facilitated by Fungi in Subsoil. Frontiers in Environmental Science (2018).
4. Soil organic carbon, extracellular polymeric substances (EPS), and soil structural stability as affected by previous and current land-use. Geoderma (2020).
5. Pathways of biogenically excreted organic matter into soil aggregates. Soil Biology and Biochemistry (2022).
6. Importance of substrate quality and clay content on microbial extracellular polymeric substances production and aggregate stability in soils. Biology and Fertility of Soils (2022).