2. Basic Physical Characteristics of Soils

Soil as a specific type of porous media known as a capillary porous medium is described, and its basic physical properties are defined. Because soil is a three-phase system, composed of solid, liquid and gaseous components, the basic properties of all three phases are described and quantified. Definitions of soil porosity, specific bulk density, bulk density, aeration, soil water content and soil specific surface are presented. Soil texture is defined and methods of soil texture (mechanical composition) determination are described (sieving, sedimentation method, pipette method, hydrometric method, laser-diffraction method) and their specific features are briefly mentioned. Pedogenetic factors and processes and their role in soil pedogenesis of various soil types are described, as well as their role in the formation of soil physical properties. The influence of clay minerals in soil physical properties formation and mechanisms of their interaction with soil water are demonstrated.