Effects of DLVO, hydration and osmotic forces among soil particles on water infiltration

Abstract

SummarySoil water infiltration is closely associated with the transport of nutrients and contaminants in soil. The physical mechanism by which electrolyte concentration influences water infiltration is not clear, however. Recent studies have shown that interaction forces between soil particles play a crucial role in the stability of soil aggregates and pores, which further affects soil water infiltration. In this research, column experiments were used to elucidate the effects of soil particle interaction forces on water infiltration in a permanently charged and a variably charged soil using different concentrations of KNO3 solutions (0.0001, 0.001, 0.01 and 0.1 mol l−1), and some interesting results on soil water infiltration were discovered. They indicated that: (i) four forces in soil (long‐range van der Waals attractive, electrostatic repulsive, hydration and osmotic repulsive forces) co‐determined the rate of soil water infiltration for both soil types tested, (ii) at smaller soil water content (large electrolyte concentration) the osmotic repulsive force became more important in soil water infiltration, and yet with a larger water content (small electrolyte concentration) the electrostatic repulsive force became more important, and (iii) the osmotic force affected water infiltration through its effect on particle interaction forces rather than its influence on the osmotic potential of water. This paper presents a quantitative description of how particle interaction forces affect water infiltration into soil.HighlightsElucidation of physical mechanisms of effects of clay charge and electrolyte concentration on soil water infiltration. Quantified effects of interaction forces of soil particles on soil water infiltration. Electrostatic repulsive and osmotic forces play a critical role in water infiltration. DLVO, hydration and osmotic forces among soil particles co‐determined soil water infiltration rate.