ABSTRACT
This chapter focuses on the physical interactions of soil grains, water, organic matter, and soil gases, and discusses how they work together in a complex environment. It presents the physical factors which are essential to the understanding of soil functions. The chapter also discusses water in its basic forms. The physical properties (principally for soil physics: density, viscosity, and surface tension) of water are also a function of its chemical structure. Several factors are important to evaluating water in soil; among these factors are: soil wetness (moisture content), free energy per unit mass (potential), and pressure (matric potential). Electrical conductivity of soil is directly affected by the soil’s water content, texture, and proportion of soluble salts. The chapter also presents soil particle organization (structure), and fluid (water and air) storage in and transportation through the soil. It discusses briefly the regimen of heat flow and soil temperature.
