Which amendment raises soil pH?

Which amendment raises soil pH?

• A. Lime
• B. Sulfur
• C. Nitrogen
• D. Phosphorus

Answer: (A)

Raising soil pH happens by adding a basic material that neutralizes acidity in the soil. Lime is the classic choice because it contains calcium carbonate (and sometimes magnesium carbonate). When lime dissolves, carbonate ions neutralize hydrogen ions and exchangeable aluminum on soil particles, reducing soil acidity and increasing pH. It also supplies calcium (and sometimes magnesium), which helps plant nutrition and soil structure. So lime moves the pH toward neutral or slightly alkaline, depending on how much is used and the soil’s buffering. Sulfur lowers pH because it is oxidized in the soil to sulfuric acid. Nitrogen fertilizers, especially in ammonium form, tend to acidify soil over time during nitrification. Phosphorus fertilizers don’t meaningfully raise soil pH.

Raising soil pH happens by adding a basic material that neutralizes acidity in the soil. Lime is the classic choice because it contains calcium carbonate (and sometimes magnesium carbonate). When lime dissolves, carbonate ions neutralize hydrogen ions and exchangeable aluminum on soil particles, reducing soil acidity and increasing pH. It also supplies calcium (and sometimes magnesium), which helps plant nutrition and soil structure. So lime moves the pH toward neutral or slightly alkaline, depending on how much is used and the soil’s buffering.

Sulfur lowers pH because it is oxidized in the soil to sulfuric acid. Nitrogen fertilizers, especially in ammonium form, tend to acidify soil over time during nitrification. Phosphorus fertilizers don’t meaningfully raise soil pH.