variable charges

variable charges

1. positive/negative charges

2. sequioxides, organic matter, kaolinite surface charges influenced by PH, ionic composition soil solution

3. humus > 2:1 expanding clay (smectite) ? 2:1 non expanding clay (Illite) > 1:1 clay (kaolinite)

4. CEC -Cation Exchange Capacity

   • cation - positive charge ion e.g ca na etc
   • Cation exchange - cations in solution exchanged for cations on exchange sites minerals and OM
   • exchangeable
   • sum exchangeable cations soil can absorb

5. anion exchange