Compute sar and evaluate sar from exchangeable cation data

Question

Answer the following questions for the soil data listed below.

         Exchangeable Cations             Cations in Saturated Extract

             (ppm Soil)                               (ppm solution)

Ca             1600                                        180

Mg               600                                          20

Na              1000                                        900

K                 600                                             5

CEC (me/100g)  =  17             pH (sat'd paste)  =  8.6

CaCO₃ (%)      =   2                 EC_se (mmho/cm)    =  4.5

a. Calculate CEC and compare with measured CEC.  Suggest a reason why the two values may be different.

b. Calculate SAR and estimate SAR from the exchangeable cation data.

c. Calculate and estimate ESR and ESP.