Question

Consider a soil with CEC = 35 cmol_c/kg holding the following amount of exchangeable cations: 13 cmol_c/kg of Ca²⁺, 6 cmol_c/kg of Mg²⁺, 4 cmol_c/kg of K⁺, 3 cmol_c/kg of Na⁺, 3 cmol_c/kg of H⁺, and 6 cmol_c/kg of Al^{3+ please show all work}

^{Calculate its percent acid saturation (%A.S.) and calculate its percent base saturation (%B.S.)}

Answer 1

cation exchange capacity-CEC

Soil-cation exchange capacity = 35 cmolc/Kg = 35 meq/100gm

Exchangeable cations

Hydrogen,H+ = 3cmolc/kg =3meq/100g

Ca2+ = 13cmolc/kg =13meq/100g

Mg2+ = 6cmolc/kg =6meq/100g

K+ = 4 cmolc/kg =4 meq/100g

Na+ = 3 cmolc/kg =3meq/100g

Al3+ = 6cmolc/kg =6meq/100g

Percent base saturation (%BS) is

%BS = 100 x sum of exchangeable cations / CEC = 100 x Basic cations / CEC

percent exchangeable basic cation saturation = 100 x 32/35 = 91.42%

percent of the exchangeable hydrogen saturation = 100 x 3/35 = 8.57%