Answer to Question #123999 in Chemistry for Meek

Question

Explain buffering mechanism in soils.

Answer 1

Three main pH buffering mechanisms are known:

1. buffering by carbonates in soils with high pH (> 7.5)

2. buffering by cation exchange capacity in soils with intermediate pH (4.5–7.5)

3. buffering by aluminium compounds in soils with low pH (< 4.5)

Sandy soils acidify faster due to the lower buffering capacity. However, the pH can be recovered more efficiently and faster compared to clay soils. Soils with high clay or organic matter content have a greater number of surface sites that keep protons and are able to resist reduced pH. Overall, clays are better buffered than loams, that are better buffered than sands.