One or all of the primary nutrients N-P-K (Nitrogen, Phosphorus, or Potassium) or the secondary nutrients magnesium (Mg) and calcium (Ca).
Merriam-Webster Online Dictionary
macronutrient (noun)1.
a chemical element (as nitrogen, phosphorus, or potassium) of which relatively large quantities are essential to the growth and health of a plant
2.
a substance (as protein or carbohydrate) essential in large amounts to the growth and health of an animal - compare micronutrient 2
primary nutrient, essential nutrient, major nutrient, key nutrient, vital nutrient
