Which of the following elements is classified as a secondary element for plants?

Sulphur is classified as a secondary macronutrient for plants because it is required in smaller quantities than primary macronutrients like nitrogen, phosphorus, and potassium but is still essential for plant growth and development. It plays a critical role in the synthesis of amino acids, proteins, and enzymes, contributing to the overall metabolic processes in plants. Secondary nutrients include elements that are vital for plants but not in as high a demand as the primary nutrients.

In contrast, nitrogen, phosphorus, and potassium are considered primary macronutrients, as they are needed in larger amounts for essential functions such as photosynthesis, energy transfer, and cellular structure. Understanding the classification of these nutrients allows for more effective fertilization strategies and better crop management practices, ensuring plants receive the right balance of nutrients for optimal growth.