Mikroaggregate

Mikroaggregate are the smallest stable soil aggregates, typically 0.01 to 0.25 millimeters in diameter, distinguished from macroaggregates, which are larger than 0.25 millimeters. They consist of mineral particles bound by clay minerals and oxides, coated with organic matter and stabilized by biopolymers produced by microbes and plant roots. Formation involves chemical adhesion of particles through cations such as calcium and magnesium, cementation by iron and aluminum oxides, and biological glue like extracellular polysaccharides and fungal hyphae that enmesh organic residues, creating a network that stabilizes mikroaggregates within soil structure.

Mikroaggregate-rich soils tend to store carbon more effectively, as organic matter occluded within microaggregates is relatively protected from microbial decay. They also contribute to soil physical properties by maintaining porosity and improving water retention, aeration, and nutrient localization, influencing the availability of nutrients such as phosphorus and base cations.

Measurement and assessment: the microaggregate fraction is typically determined by wet sieving or density-based fractionation after removing larger macroaggregates. Contents and stability are influenced by soil texture, moisture regime, and management. Agricultural practices that increase soil organic matter and promote fungal-dominated decomposition, such as reduced tillage and cover cropping, often enhance mikroaggregation over time.

In summary, Mikroaggregate are a key component of soil structure and carbon stabilization, linking fine mineral fractions with organic matter to support soil health and fertility.