Which statement best distinguishes a complete fertilizer from an incomplete fertilizer?

• A. A complete fertilizer contains all three primary nutrients N, P, and K; an incomplete fertilizer is missing one or more.
• B. A complete fertilizer contains only nitrogen.
• C. A complete fertilizer contains all micronutrients.
• D. A complete fertilizer contains no primary nutrients.

Answer: (C)

A complete fertilizer is intended to supply the full range of essential nutrients a plant needs, including both macronutrients and micronutrients. That means it provides the three primary macronutrients (nitrogen, phosphorus, potassium) plus the trace elements plants require in smaller amounts, such as iron, zinc, manganese, copper, boron, molybdenum, and others. Because missing any essential nutrient can limit growth, the statement that a complete fertilizer contains all micronutrients best captures this broader, full-spectrum supply.

If a fertilizer only supplies nitrogen, it would be missing phosphorus, potassium, and many micronutrients, so it wouldn’t be complete. Some products might deliver the three primary nutrients but not all micronutrients, which would still be incomplete. Conversely, a fertilizer with no primary nutrients would fail to meet the plants’ basic macronutrient needs.