Full explanation
Formula: CEC = sum of all exchangeable cations per 100 g of soil. Components: (1) clay particles (montmorillonite 80–150, kaolinite 3–15 cmol(+)/kg); (2) humus (100–300 cmol(+)/kg — 5–10× higher than clay, so each +1% humus = +5–15 cmol(+)/kg); (3) organo-mineral complexes. Ukrainian categories per DSTU 4362:2004: high (>30), medium (20–30), low (<20). Farmer implications: (1) LOW-CEC SOILS (sandy, sod-podzolic) — fast K, Ca, Mg leaching; needs frequent small doses; (2) HIGH CEC (chernozems) — K and Ca can be spread every 2–4 years at 200–400 kg/ha without major losses; (3) Base Saturation (BS%) — share of «useful» cations (Ca²⁺, Mg²⁺, K⁺) in total CEC. Lab test: Mehlich-Hagelberg method.