text: Liming can also improve aggregate stability on clay soils. For this purpose structure lime, products containing calcium oxide (CaO) or hydroxide (Ca(OH)) in mixes with calcium carbonate (CaCO), are often used. Structure liming can reduce losses of clay and nutrients from soil aggregates. The degree to which a given amount of lime per unit of soil volume will increase soil pH depends on the buffer capacity of the soil (this is generally related to soil cation exchange capacity or CEC). 
  Most acid soils are saturated with aluminum rather than hydrogen ions. The acidity of the soil is therefore a result of hydrolysis of aluminum.  This concept of "corrected lime potential" to define the degree of base saturation in soils became the basis for procedures now used in soil testing laboratories to determine the "lime requirement" of soils.
  Soils with low CEC will usually show a more marked pH increase than soils with high CEC. But the low-CEC soils will witness more rapid leaching of the added bases, and so will see a quicker return to original acidity unless additional liming is done. Over-liming is most likely to occur on soil that has low CEC, such as sand which is deficient in buffering agents such as organic matter and clay.