I agree with@Femi Abiodun

CEC is a the intrinsic ability of a soil to adsorb cations (nutrients) which is later released for crop uptake. It can also be defined as a measure of negatively charged sites on the soil surface.

Effective cation exchange capacity (ECEC) is one of the methods of determining CEC. Quantitatively, it is the total amount of exchangeable cations i.e exchangeable bases (calcium, magnesium, potassium and sodium)plus exchangeable aluminum in the soil. It is mostly used in acidic soils. ECEC gives a measure of the CEC of a soil at field pH.

Simply put, bases produces negative ions in solution.

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I agree with@Femi Abiodun