Cation Exchange Capacity (CEC) is a measure of a soil’s ability to retain and exchange positively charged ions (cations) such as calcium, magnesium, potassium, and sodium. It reflects the total negative charge available on soil particles, which originates primarily from the surfaces of clay minerals and organic matter.
Clay minerals contribute to CEC through isomorphic substitution within their crystal lattices, creating permanent negative charges. Organic matter adds variable charge sites that become negative when deprotonated. The combined effect of these components determines the overall nutrient holding capacity of the soil.
C_{\text{clay}} = CEC contributed per % of clay (cmolc/kg/% clay)
C_{\text{OM}} = CEC contributed per % of organic matter (cmolc/kg/% OM)
Understanding and mapping CEC is essential for agronomy, landβuse planning, and environmental assessment. Areas with higher CEC can retain more nutrients and buffer pH changes, influencing crop productivity and ecosystem health.
What is Cation Exchange Capacity?
How does clay contribute to CEC?
What role does organic matter play in CEC?
Why is CEC important for soil health?
How do I test for Cation Exchange Capacity?
Can CEC be improved?
What units are used for measuring CEC?
Results are for informational purposes only and do not constitute professional advice.
