Gypsum is applied to the soil as a source of ?

Gypsum, chemically known as calcium sulphate dihydrate (CaSO₄·2H₂O), is an important mineral used in agriculture as a soil conditioner and nutrient source. When applied to soil, gypsum provides two vital elements — calcium (Ca) and sulphur (S) — both of which are essential for healthy plant growth and maintaining soil fertility.

Calcium plays a key role in improving soil structure. It helps to reduce soil compaction, enhances aeration, and promotes better water infiltration. Calcium ions replace sodium ions in sodic soils, which helps to reclaim saline and alkaline soils by improving their texture and making them more suitable for root development. In plants, calcium is a structural component of cell walls and membranes, helping to strengthen tissues and promote proper growth.

Sulphur, the other major nutrient in gypsum, is crucial for protein synthesis and the formation of chlorophyll in plants. It is also a part of several amino acids, such as cysteine and methionine, and contributes to the overall metabolic activity of crops. Sulphur deficiency in soil often leads to poor crop yield, yellowing of leaves, and stunted growth.

Unlike lime (CaCO₃), gypsum does not significantly change the soil’s pH, making it suitable for acidic as well as neutral soils. Its solubility ensures that the nutrients are readily available to plants. Therefore, gypsum is widely used for crops like groundnut, wheat, rice, and legumes, where both calcium and sulphur are required.

In summary, gypsum serves as a dual nutrient source of calcium and sulphur, improving soil structure and fertility without altering soil pH — making it an essential agricultural chemical and a key topic in Inorganic Chemistry MCQs