What is cation exchange capacity of plants ?
Cation exchange capacity is the sum of the exchangeable cations that a soil can absorb is called as cation exchange capacity.
Cation exchange capacity can also be defined as “the amount of cationic species bound at pH of 7.0″.
Table showing the range of Cation Exchange capacity in plants
|Soil texture||CEC (meq/100gm)|
|Sand (light colour)||3-5|
|Sand (dark colour)||10-20|
|Clay and clay loam||20-50|
Humus has the highest cation exchange capacity around 200 to 400
Calculating cation exchange capacity formula
Cation exchange capacity formula can be found out be using this formula
Cation Exchange Capacity = Base cations + Acid cations
(Ca2+ + Mg2+ + K+ + Na+) + (H+ + Al3+ + NH4+)
Clay minerals and cation Exchange capacity in soils
- CEC and specific area of the clay minerals are in the order: smectite > fine mica > kaolinite
- Higher the Cation Exchange Capacity more resistance soil has to changes in pH.
- Higher CEC soils require more lime than those with low CEC’s to achieve the same pH change.
- CEC increases with fineness of the soil particles, this means increasing clay content will increase the Cation Exchange Capacity
- When pH of the soil solution increases the CEC will also increase.
- Soil dominated with montmorillonite and vermiculite have higher CEC than those dominated with kaolinite, chlorite or illite.
- CEC of Mica is Zero.