Chemical properties | FAO SOILS PORTAL | Food and ...
There are acidforming cations (hydrogen and aluminium) and there are baseforming cations (calcium, magnesium, potassium and sodium).The fraction of the baseforming cations that occupy positions on the soil colloids is called the base saturation percentage. When the soil pH is 7 (neutral), base saturation is 100 percent and there are no hydrogen ions stored on the colloids.