Microstructure of Soils of Different Geneses and Its Transformation in Constructozems of Moscow

Abstract

The transformation of microstructure of constructozems was studied in a four-year-long (2012–2016) field experiment with the use of rheological and electron microscopy methods. Field studies were performed in the area of Moscow State University on three variants of artificial human-made soils (constructozems) differing in the structure of their profiles: (1) the control variant with the upper part composed of a homogenized Ap horizon, (2) the layered constructozem composed of a sequence of layers (Ap–peat–sand–Ap), and (3) the constructozem consisting of a mixture of the above-mentioned horizons. Electron microscopy attested to an increase in differentiation of the pore space in the upper Ap horizons in variants 1 and 2: new pores and chambers of different sizes appeared. In the loose porous mass of the peat layer in variant 2, more compact cohesive microstructures were formed. Microaggregation was identified in the upper layer of variant 3. Changes in the spatial arrangement of the solid phase of the soils were reflected in their rheological properties. A gradual increase in stability of structural bonds in the Ap horizon (variant 1) was detected. In variant 2, the underlying peat layer affected the shape of rheological curves in the Ap horizon. In variant 3, changes in strength properties of the mixed soil mass resulted in the formation of rheological behavior of fluid bodies typical of the plowed humus horizons.