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PLS 671: Environmental Soil Chemistry
 

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Effective Cation Exchange Capacity (ECEC)
by the Summation Method
  
 





  A.)  Procedure:




1.)  Weigh 2.0g of <2mm air-dried soil in duplicate into 40mL centrifuge tubes.



2.)  Add 25mL of 1M  NH4OAc (ammonium acetate) buffered to pH 7, cap the tubes, and
       shake for 30 min.



3.)  Centrifuge the tubes at 2,000 rpm for 10 min.



4.)   Pour the supernatant into labeled 50mL volumetric flasks.
 

5.)  Repeat steps 1-4 with an additional 25mL of 1M NH4OAc



6.)  Bring the flasks up to volume of 50mL.



7.)  Measure concentrations of Ca2+, Mg2+, K+, and Na+ in the extracts using appropriate
       standards.



8.)  Calculate ECEC by summation of the exchangable bases and express on an oven-dried weight
        basis.