Which amendment is commonly used to raise soil pH in many garden soils?

• A. Sulfur.
• B. Compost.
• C. Lime.
• D. Peat moss.

Answer: (C)

When soil pH is too acidic, lime is the go-to amendment for raising pH. Lime neutralizes excess hydrogen ions in the soil solution and adds calcium (and often magnesium) to the soil’s exchange sites. This combination raises the pH toward neutral and also improves nutrient availability because many nutrients become more available as conditions become less acidic. The speed and extent of the effect depend on soil texture, current pH, and how finely the lime is ground—finer lime reacts faster. Calcitic lime (calcium carbonate) and dolomitic lime (calcium magnesium carbonate) are common forms.

Sulfur lowers pH by forming sulfuric acid in the soil, so it’s used to acidify, not to raise pH. Compost improves soil structure and biology and can buffer pH, but it’s not a reliable method for raising pH to a target level. Peat moss is acidic and tends to lower pH, not raise it.