Soils as the Skyscrapers - Soil: The Skin of the Planet Earth - page 78

to be successful and easily applicable for derivation of theories on fl ow of water and
solutes in soil. We shall use one of them in the next two chapters (Fig. 7.3 ).
We should remember that the above models - one composed of spheres and the
other being an assembly of very fi ne tubes - are still very distant from reality.
Nevertheless, they continue to be presented in textbooks for explaining basic ideas
about soil pores and their role in the majority of processes that occur within soils. A
somewhat better model exists when tubes having variable radii along their lengths
are connected by spheres (Fig. 7.4 ).
Fig. 7.3 Pores modeled as an
ensemble of parallel
cylindrical tubes with each
having a different radius
Fig. 7.4 Model of soil porous system consisting of a combination of spheres and tubes, both of
which vary in size