3. Soil exchangeable acidit Exchangeable acidity- The aluminum and hydrogen that can be replaced from an acid soil by an unbuffered salt solution such as KCI or NaCl(cmol (+)/kg)3. Soil exchangeable acidity • Exchangeable acidity- The aluminum and hydrogen that can be replaced from an acid soil by an unbuffered salt solution such as KCl or NaCl. (cmol（＋）/kg）