Surface area largely determines many physical and chemical properties
of materials. Physical adsorption of molecules, heat loss or gain resulting
from that adsorption, swelling and shrinking, and many other physical
and chemical processes are closely related to surface area. Surface or
exposed area is also closely related to and often the controlling factor in
many biological processes. Soils vary widely in their reactive surface
because of differences in mineralogical and organic composition and in
their particle-size distribution. Water retention and movement, cation
exchange capacity, and pesticide adsorption are closely related to the
specific surface (defined as the surface area per unit mass of soil). Specific
surface is usually expressed in square meters per gram (m2/g)
