Which of the following statements is true about the three primary nutrients represented on fertilizer labels?

• A. They are Nitrogen, Phosphorus and Potassium
• B. They are Nitrogen, Phosphorus and Calcium
• C. They are Nitrogen, Potassium and Magnesium
• D. They are Phosphorus, Potassium and Calcium

Answer: (A)

Plants rely on macronutrients in the largest amounts, and the three primary ones are nitrogen, phosphorus, and potassium. Fertilizer labels use N-P-K to show how much of each of these big three nutrients is present, typically as percentages by weight (often written as N, P2O5, K2O, though many labels simply show N, P, K). Each plays a distinct role: nitrogen fuels leafy growth, phosphorus supports root development and flowering, and potassium helps overall plant health, water regulation, and resilience against stress.

Calcium, magnesium, and sulfur are secondary nutrients, needed in smaller amounts, which is why they aren’t included among the three primary nutrients on standard fertilizer labels. So the statement that the three primary nutrients represented on fertilizer labels are nitrogen, phosphorus, and potassium is correct.