Abstract <p>Fractionation of the clay fraction was carried out and the mineral composition of clay and its subfractions in the soil of the rhizosphere of the Norway maple (<i>Acer platanoides</i> L.) and in the bulk soil from the AELoa horizon of podzolic soil was studied. It was found that the clay fraction is dominated by a 1–0.2 μm subfraction (56% in the rhizosphere of maple and 60% in the bulk soil) and contains 20% of 0.2‒0.06 μm subfraction in the rhizosphere and 27% of this fraction in the bulk soil. The content of 0.06‒0.02 and &lt;0.02 μm subfractions did not exceed 10%. A significant increase was revealed in the proportion of 0.06‒0.02&#xa0;μm subfraction and a decrease in the proportion of &lt;0.02 μm subfraction in the rhizosphere compared with the bulk soil. The size fractions of clay both in the rhizosphere and in the bulk soil are differentiated by their mineral composition. The 1‒0.2 μm fraction is dominated by kaolinite; the proportion of micas increased and the proportion of kaolinite decreased in the 0.2‒0.02 μm fraction, while in the &lt;0.02 μm fraction the proportion of labile minerals significantly increases. There was no significant difference in the mineral composition of the clay fraction and the 1‒0.2 μm subfraction. It was found that the 0.2‒0.02 μm subfraction in the rhizosphere contains significantly more labile minerals compared to the bulk one, which are a result of intensively occurring mica transformation processes into labile structures in the rhizosphere.</p>