Certified Storm Water Operator Practice Exam

What must be added to soil to lower acidity and increase the pH?

1. Sulfur

2. Compost

3. Lime

4. Sand

The correct answer is: Lime

To lower acidity in soil and increase its pH, lime must be added. Lime, typically in the form of calcium carbonate, serves as a fundamental soil amendment primarily used to raise soil pH levels. When lime is applied to acidic soils, it reacts with the hydrogen ions that contribute to acidity, effectively neutralizing them. This process leads to a less acidic environment, or a higher pH, which is beneficial for many plants that prefer neutral to slightly alkaline conditions. On the other hand, sulfur is often used to lower soil pH, making it more acidic, while compost can improve soil structure and provide organic matter but does not specifically address pH issues in the same manner as lime. Sand primarily affects soil texture and drainage but does not have any direct effect on soil acidity. Therefore, the role of lime as a pH enhancer makes it the correct choice for raising soil acidity levels.