Which material is used to lower soil pH?

• A. Limestone
• B. Quicklime
• C. Elemental sulfur
• D. Magnesium carbonate

Answer: (C)

Elemental sulfur lowers soil pH. When you add sulfur to soil, soil bacteria oxidize it to sulfuric acid, increasing the soil’s acidity and dropping the pH gradually over time. This slow acidification is useful when you need to reduce pH for plants that prefer more acidic soils or to unlock certain nutrients that become more available in lower pH.

In contrast, limestone and magnesium carbonate are liming materials that raise pH by neutralizing acidity. Quicklime also raises pH, often quickly and more aggressively, which can risk overshooting the target if not careful. So, when the goal is to lower pH, elemental sulfur is the appropriate choice.