Which of the following calcium sources should not be used as a lime source?

The appropriate response regarding the use of various calcium sources in lime application focuses on the nature and purpose of each substance. Gypsum, while it is a source of calcium, does not serve as a lime source because its primary function is to supply calcium and sulfur to the soil without affecting pH levels significantly. Unlike lime sources, which are used to increase soil pH and address acidity, gypsum does not provide this benefit. Instead, it is typically used to improve soil structure and drainage, especially in sodium-affected soils.

In contrast, dolomitic lime, calcium carbonate, and calcium hydroxide are intended to modify soil acidity and increase pH. They actively contribute to reducing the acidity of soils, which is often necessary for enhancing plant growth and nutrient availability. Therefore, gypsum's role distinguishes it from true lime sources, aligning with the principles of soil amendments in agricultural practices.