AEC

Anion exchange capacity should be thought of as the soils ability to remove anions from the soil water solution and sequester those for later exchange as the plant roots release carbonate anions to the solution. Those colloids that have low CEC tend to have some AEC. Amorphous and sesquioxide clays have the highest AEC followed by the iron oxides. The levels of AEC is much lower than for CEC. Phosphates tend to be held at anion exchange sites.