From simple clay content, CEC of soil cannot be made. Soil CEC involves the contribution of OC and clay mineral type..

Dear Dr.Dilip Kumar Pal..

Thanks for your response..

Like you said the OC is very imporant in determination of CEC but my soil sample is removed from organic matter..

Best Regards..

Dear Mr. Aldhahi,

the major driver for the CEC in rocks and soil is the smectite content. With this in mind high smectite contents will also yield high CEC. This is a correlativ relationship it does not compensate for a precise determination of the CEC as shown in

Meier, L.P., Kahr, G., 1999. Determination of the cation exchange capacity (CEC) of clay

minerals using the complexes of Copper (II) ion with triethylenetetramine and

tretraethylenepentamine. Clay Clay Miner. 47, 386–388

H.G.Dill

Dear Dr. Harald G. Dill...

Thank you for your answer for my question, Yes exactly, semectite group characterize by high CEC, but in my country located in arid Environment and there is relative similarity in clay minerals distribution, and in my question I was wondering if we can put an equation for estimation CEC from Clay content and /or organic matter..

Regards

Dear Mr. Aldhahi,

I would not go beyond that line which I drew in my answer. Using the smectite content as a direct correlation with the CEC would go a bit too far because of the complexity of the smectite-group minerals and the tendency to share mixed-layer structures, predominantly with illite. The organic part does not play such a role in arid climatic zones whereas the content of smectite- and hormite-group phyllosilicates may be rather high.

see:

DILL, H.G. (2017) Residual clay deposits on basement rocks: The impact of climate and the geological setting on supergene argillitization in the Bohemian

Massif (Central Europe) and across the globe.- Earth Sciences Reviews 165: 1-58.

DILL, H.G. (2016) Kaolin: soil, rock and ore From the mineral to the magmatic, sedimentary, and metamorphic environments.- Earth Sciences Reviews 161: 16-129

With kind regards

H.G.Dill

A useful reference is the textbook entitled “Fundamentals of Soil Behvior“ by James K. Mitchell

EPA has a simple method to determine the CEC:

SW-846 Test Method 9081: Cation-Exchange Capacity of Soils (Sodium Acetate)

https://www.epa.gov/hw-sw846/sw-846-test-method-9081-cation-exchange-capacity-soils-sodium-acetate

Dear Dr. Azm Shaher..

I am very gratful for your help by giving me a usful reference.

Best regards

Dear Mr. Hamzah Alhashemi..

Thank you very much for your assistance..

Regards