A low pH can be raised by adding which chemical?

Lime is commonly used to raise the pH of acidic soils, making it less acidic and improving the overall soil condition for plant growth. Lime contains calcium carbonate or calcium oxide, which react with the hydrogen ions in the soil, effectively neutralizing the acidity. This process increases the pH level, creating a more favorable environment for nutrient availability and root development.

Using gypsum does not significantly affect soil pH; it primarily provides calcium and sulfur to the soil without altering acidity levels. Ammonium nitrate is an acidic fertilizer that may further lower soil pH, while potassium chloride, used mainly to supply potassium, also does not have a significant impact on raising pH. Thus, lime is the best choice for effectively increasing soil pH.