Silicic acid can sorb on positively charged sites of Fe oxide-rich kaolinitic soil clays.
Resulting decrease in ζ is a key factor for dispersion of the clay fraction.
The clearest effect of silicic acid on clay dispersion was seen at pH range from 4 to 6.
Effect of silicic acid can be obscured in strongly acidic or alkaline conditions.
Silicic acid may act as an enhancer to transport more Si sink (clays) from terrestrial soils into the oceans.