Which of the following nutrients is not one of the three major nutrients typically indicated on a fertilizer?

The primary nutrients typically indicated on a fertilizer label are nitrogen, phosphorus, and potassium, often referred to as N-P-K. These three nutrients play essential roles in plant growth: nitrogen is crucial for leaf and stem development, phosphorus supports root formation and flowering, and potassium is necessary for overall plant health and disease resistance.

Calcium, while important for plant structure and cellular processes, is classified as a secondary nutrient, rather than a major nutrient. It contributes to cell wall stability and supports various physiological functions, but it does not usually appear on the main fertilizer label that highlights the three primary macronutrients. This distinction is significant in understanding fertilizer composition and nutrient management in agriculture.