Cation Exchange Capacity or CEC of a soil is
basically the soils ability to hold onto nutrients
and make them available (or unavailable) to plant
roots. Clay particles (and
have a high CEC number and will hold onto nutrients
very tightly. Sand on the other extreme has a very
low CEC and holds little chemical attraction for
these nutrients. Therefore, they will easily move
through a sandy soil and be lost to the plants.
According to the following chart, a soil with a CEC
of 6 would be a sandy soil while one with a CEC of
over 40 has mostly clay in its makeup.