Oak
Birch tree
Pine
Modrida
Glade
Fallow
Arable
land
Capillary moisture content, %
Total moisture content, %
Figure 2. Hydrophysical parameters of typical black soils under different
vegetation cover
Source: Developed by the authors
Density and porosity. The structural state of the soil is the most conservative index
which has a high degree of stability. It is most convenient to describe the structural
state in terms of differential porosity (the ratio of texture and structural spaces,
occupied by water and air). During mechanical compaction, the texture porosity of soil
(in the dry state) should not change, since it is stipulated with physical and chemical
properties of solid phase's surface (is a function of the material composition of soil's
solid phase).
The structural porosity changes due to the reduction of large pores and cracks
(when soil material from overlying layers falls into them or when it is pressed from
adjacent layers), which leads to a decrease in texture porosity in wet state because of
lateral earth pressure of expanded soil mass and simultaneous change of the whole
complex of soil's physical properties, connected with the structure of pore space.
The parameters of pore space's structure are important for assessment of its
rearrangement as a result of mechanical impact and evolution of compacted soils. The
dynamics of the properties of soil's solid phase is also expressed via changes in specific
gravity and volumetric weight, porosity, and others.
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