Answer: Nitrogen-Phosphorus-Kalium (potassium).
- A Nitrogen-Phosphorus-Potassium, the three macronutrients
- B Nitrogen-Protein-Krypton, an invalid combination
- C Nitrite-Phosphate-Kelp, not a real fertilizer label
- D Nitrogen-Phosphorus-Kalium (potassium)
Correct answer: D. Nitrogen-Phosphorus-Kalium (potassium)
Explanation: NPK fertilizers contain Nitrogen (N), Phosphorus (P), and Potassium (K, from Kalium). These are the three macronutrients most commonly deficient in agricultural soils and most important for plant growth.
Atmospheric N₂ is fixed into ammonia by nitrogen-fixing bacteria (protected from oxygen by leghaemoglobin in root nodules), converted to nitrate via nitrification for plant uptake, and eventually returned to the atmosphere as N₂ via denitrification, completing the cycle.
Concept context
Essential mineral elements, their roles and deficiency symptoms. Nitrogen fixation and soil nutrition.