pH / BS

Ok, I think what is confusing me is buffering capacity...

Sandra mentioned in the review session that the difference between the active acidity and exchangeable acidity relates to the buffering capacity. The smaller the difference is the higher the buffering capacity, is what I thought she said. I'm trying to relate that to other concepts to understand it better.

re: pH in water versus pH in CaCl₂

pH in water measures the pH of soil solution

pH in CaCl₂ measures exchangeable acidity (thus pH in CaCl₂ will be lower than pH in water). The lower the pH in CaCl₂ relative to the pH in H₂O, the greater the exchangeable acidity.