Soil Aggregate Breakdown with Colloidal Particles Release and Transport in Soil: A Perspective from Column Experiments

The strongest fortresses often disintegrate from the inside. Likewise, soil internal forces play a critical role in the initial breakdown process of soil aggregate, thus accelerating soil erosion and the release of soil colloid particles. To date, research on the effect of soil internal forces, especially separating the electrostatic force, and on the process of soil aggregate breakdown with particle release and transport in soil is largely inadequate. Therefore, column experiments were used to investigate the properties of transport and soil particles released from the disintegration of model soil aggregates caused by different levels of electrostatic forces. We found that the increase of electrostatic repulsive pressure was the immediate cause of soil aggregate breakdown, that the highest concentration of released soil particles could reach 808.36 mg L-1, and that the mean particle sizes of the released soil ranged from 100 nm to 300 nm. The particle size distributions and clay mineral composition of the released soil particles were not dominated by the electrostatic force. In practice, the change of external conditions of agricultural soil would lead to the change of soil internal forces, then affect soil aggregate stability. This study aims to provide a micro perspective to understand the release of fine particles from soil matrix and its implication for agricultural soil.