Which material is used to raise soil pH?

Which material is used to raise soil pH?

• A. Elemental sulfur
• B. Iron sulfate
• C. Aluminum sulfate
• D. Limestone

Answer: (D)

Raising soil pH means making the soil less acidic by neutralizing hydrogen ions and exchangeable acidity. Limestone is the go-to material for this because it is a base that dissolves slowly in the soil, releasing carbonate ions and calcium ions. The carbonate reacts with the acidity in the soil solution and with exchangeable acidity, gradually increasing the pH toward neutral. If a dolomitic limestone is used, it also adds magnesium along with calcium, which can be desirable for some soils. The other materials push pH downward. Elemental sulfur must be oxidized by soil bacteria to form sulfuric acid, which lowers pH over time. Iron sulfate and aluminum sulfate also acidify the soil; they release acidic ions and can supply micronutrients, but they are not used to raise pH. So limestone is the material used to raise soil pH.

Raising soil pH means making the soil less acidic by neutralizing hydrogen ions and exchangeable acidity. Limestone is the go-to material for this because it is a base that dissolves slowly in the soil, releasing carbonate ions and calcium ions. The carbonate reacts with the acidity in the soil solution and with exchangeable acidity, gradually increasing the pH toward neutral. If a dolomitic limestone is used, it also adds magnesium along with calcium, which can be desirable for some soils.

The other materials push pH downward. Elemental sulfur must be oxidized by soil bacteria to form sulfuric acid, which lowers pH over time. Iron sulfate and aluminum sulfate also acidify the soil; they release acidic ions and can supply micronutrients, but they are not used to raise pH.

So limestone is the material used to raise soil pH.