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 is achieved primarily with lime. Lime, like calcitic or dolomitic lime, neutralizes soil acidity and supplies basic cations (calcium and sometimes magnesium) that occupy exchange sites on soil particles. As lime dissolves, carbonate from the lime neutralizes hydrogen and aluminum on the cation exchange complex, which lowers acidity and raises pH. The calcium and magnesium ions that enter the soil help push acidic cations off the exchange sites, increasing the proportion of exchangeable bases and thus raising base saturation. Sulfur acidifies soil rather than raises pH, so it’s used to lower pH in very high-pH soils or to adjust certain nutrient availability, not to raise pH. Gypsum adds calcium and sulfur but does not significantly raise soil pH on its own and is not a primary tool for increasing base saturation. Organic matter improves soil structure, nutrient holding, and buffering capacity and can influence pH over time, but it is not the standard amendment for reliably raising soil pH. Lime remains the go-to amendment for increasing pH and adjusting base saturation.

Raising soil pH and increasing base saturation is achieved primarily with lime. Lime, like calcitic or dolomitic lime, neutralizes soil acidity and supplies basic cations (calcium and sometimes magnesium) that occupy exchange sites on soil particles. As lime dissolves, carbonate from the lime neutralizes hydrogen and aluminum on the cation exchange complex, which lowers acidity and raises pH. The calcium and magnesium ions that enter the soil help push acidic cations off the exchange sites, increasing the proportion of exchangeable bases and thus raising base saturation.

Sulfur acidifies soil rather than raises pH, so it’s used to lower pH in very high-pH soils or to adjust certain nutrient availability, not to raise pH. Gypsum adds calcium and sulfur but does not significantly raise soil pH on its own and is not a primary tool for increasing base saturation. Organic matter improves soil structure, nutrient holding, and buffering capacity and can influence pH over time, but it is not the standard amendment for reliably raising soil pH. Lime remains the go-to amendment for increasing pH and adjusting base saturation.