Why can draining sulfide-rich cat clays make the soil too acidic for most plants?

Draining sulfide-rich "cat clays" makes soil highly acidic because the process introduces air into previously water-saturated, anaerobic environments. As long as these soils remain saturated, the sulfides remain stable. However, when the soil is drained and exposed to oxygen, the sulfides undergo oxidation to form sulfates.1

If the soil lacks sufficient basic constituents (such as lime) to neutralize these compounds, the reaction produces free sulfuric acid. This significant increase in acidity can lower the soil pH to levels that are toxic to most plants. Furthermore, highly acidic conditions promote the solubilization of other metal ions, particularly aluminum, which is harmful to plant growth. Because neutralizing these soils requires massive quantities of lime, reclamation is often impractical unless the soil naturally contains enough basic material to buffer the acid production.123