Micro nutrient fertilizers

Sixteen elements are essential for plant growth out of these Fe, Zn, Mn, Cu, B, Mo, Cl are required in small quantities. They are called tertiary or micro nutrient. The average concentration of these nutrient in soil are Mn 1000 ppm, Cl 480 ppm, Zn 80 ppm, Cu 70 ppm, B 10 ppm, Mo 2 to 3 ppm, iron 140 ppm.

Development of micro nutrient deficiency: The micro nutrient deficiency occurs under conditions of

  1. Soils with a very high organic matter content (peat and muck soils)
  2. Soils with very high or very low pH.
  3. High doses of commercial fertilizers
  4. Highly leached acid and sandy soil.
  5. Soils with impeded drainage or high water table.
  6. Over liming of the soil.
  7. Intensive cultivation.

The deficiencies may be overcome by addition of more than one micro nutrients. If more than one micronutrients are applied it is called multinutrients. The information on sources of micronutrients, their formulae and nutrient content is given in following table.

S. No.

Source (formula)

% Nutrient


Copper sulphate (CuSO4.5H2O)

25-35% Cu


Zinc sulphate (ZnSO4.7H2O)

22-35% Zn


Borax or Sod.Borate (Na2B4O7.10 H2O)

10.6% B


Manganese Sulphate (MnSO4.4H2O)

23% Mn


Ammonium Molybdate ( (NH4)6Mo7O24.4H2O)

54% Mo


Ferrous sulphate (FeSO4.7H2O)

20% Fe