Which amendment is commonly used to raise soil pH and adjust base saturation?

Which amendment is commonly used to raise soil pH and adjust base saturation?

• A. Sulfur
• B. Lime
• C. Gypsum
• D. Organic matter

Answer: (B)

Raising soil pH and increasing base saturation relies on using an amendment that neutralizes acidity and supplies basic cations to the soil’s exchange sites. Lime does exactly that: when it dissolves, carbonate reacts with hydrogen and aluminum ions in the soil, neutralizing acidity and releasing calcium (and sometimes magnesium). This calcium and magnesium then occupy exchange sites, increasing base saturation and pushing pH upward.

Sulfur acidifies the soil, so it wouldn’t raise pH. Gypsum provides calcium but does not meaningfully raise soil pH, especially in the short term. Organic matter can help buffer pH and improve overall soil health, but its effects on pH are slower and less predictable than applying lime for a direct pH increase.