What is a secondary nutrient that contributes to plant growth?

Calcium is classified as a secondary nutrient that plays a crucial role in plant growth and development. It is vital for maintaining cell walls, stimulating root growth, and facilitating the movement of other nutrients within the plant. Unlike primary nutrients, which are needed in larger quantities (such as nitrogen and phosphorus), secondary nutrients are still essential but required in smaller amounts. Although phosphorus and zinc are also important for plant health—phosphorus being a primary nutrient that aids in energy transfer and root development, and zinc being a micronutrient essential for enzyme function—they do not fall into the secondary nutrient category. Calcium specifically supports various physiological functions in plants, making it the correct choice in this context.