Soil characteristics include properties of soil that remain consistently stable unless physically disturbed by man or extreme environmental events.

Cation exchange capacity (CEC), % carbon, and % nitrogen are used to classify soil types. These soil characteristics also provide an indication of soil fertility and buffering capacity. The cation exchange capacity is also known as the base exchange capacity and is expressed in milliequivalents per 100 g of soil. Total exchangeable cations (TEC) are calculated by adding together the amounts of individual cations. It is common to find soils with Total exchangeable cations (TEC) higher than their Cation exchange capacity (CEC). An ammonium acetate solution is used to displace exchangeable cations before measurement. Many subsoils contain gypsum which dissolves in ammonium acetate solution resulting in % base saturation values greater than 100%.

The percentage base saturation = 100 x

Total exchangeable cations (TEC) / Cation exchange capacity (CEC).

The exchangeable sodium percentage (ESP) = 100 x Na/CEC.