What is the Difference Between Gypsum and Limestone?

Gypsum and limestone are both calcium-containing minerals used for soil amendments, but they have different properties and serve different purposes. Here are the key differences between gypsum and limestone:

• Chemical Composition: Gypsum is calcium sulfate (CaSO4·2H2O), while limestone is calcium carbonate (CaCO3).
• Solubility: Gypsum is more soluble than limestone, which means it can dissolve more readily in water.
• Soil pH: Limestone is an acidic mineral that can change the soil pH due to its carbonate content, while gypsum is a neutral mineral and does not change the soil pH.
• Soil Structure: Gypsum can improve soil structure by flocculating (binding) soil particles together, making it a good choice for soils with high sodium levels or poor structure.
• ** Sulfur Content**: Gypsum provides a source of sulfur, which is an essential nutrient for plant growth, while limestone does not.

In summary, gypsum and limestone both provide calcium to the soil, but gypsum also provides sulfur and does not change soil pH. Limestone, on the other hand, can raise the pH of acidic soils and provide magnesium. The choice between gypsum and limestone depends on the specific needs of your soil and the desired outcomes for your crop production.

Comparative Table: Gypsum vs Limestone

Here is a table summarizing the differences between gypsum and limestone:

Gypsum is a hydrated calcium sulfate mineral, while limestone is composed mainly of skeletal fragments of marine organisms such as coral and mollusks. Gypsum is more soluble than limestone, and it has a neutral pH, meaning it cannot change soil pH. On the other hand, limestone is an acidic mineral and can change the soil pH due to the carbonate group. Gypsum can grow into larger crystals than limestone.