Certified Crop Advisor Practice Exam

Which source is generally not recommended to be used as a lime source?

1. Dolomitic lime

2. Gypsum

3. Calcitic lime

4. Hydrated lime

The correct answer is: Gypsum

Gypsum is generally not recommended as a lime source because it primarily serves to supply calcium and sulfur nutrients to the soil but does not significantly impact soil pH. Lime sources are typically utilized to raise the pH of acidic soils, whereas gypsum does not possess this capability. It can be used in certain situations, such as improving soil structure and drainage or providing essential nutrients, but it will not effectively neutralize acidity or correct pH levels in the same way lime products do. Dolomitic lime and calcitic lime are both effective in adjusting pH and supplying calcium, with dolomitic lime also providing magnesium. Hydrated lime is another option that can significantly raise pH, although it is more caustic and should be used with care. Therefore, when the context of correcting soil acidity is considered, gypsum does not fulfill the role of a lime source.