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10
CH3041
SOIL BUFFER
CAPACITY
Soils
resist pH changes by buffering.
• Soils with low buffer capacity (no clays
or humus) are most likely to achieve low pH’s
& release phytotoxic [Al3+] with small extra H+
inputs
or humus) are most likely to achieve low pH’s
& release phytotoxic [Al3+] with small extra H+
inputs
Carbonate buffer
reservoir
H+ + CaCO3 ® HCO3- + Ca2+
Exchangeable base
cation
2H+ + Ca2+-clay ® 2H+-clay + Ca2+
Aluminosilicate
decomposition
H+ + >Al-OH]-½ ® >Al-OH2]+½
