Question: which one of the following is not an essential micronutrient for plants?
Answer: Macronutrients (nitrogen, phosphorus, potassium, calcium, magnesium and sulphur). Micronutrients (iron, copper, manganese, zinc, boron, molybdenum and chlorine). Additional mineral nutrient elements which are beneficial but not necessary are sodium, cobalt, vanadium, nickel, solenium, aluminium and silicon.