Skip to main content

Please note that this site in no longer active. You can browse through the contents.

Importance of Micronutrients

Plants need certain nutrients, other than the nutrients which were discussed in the previous two lessons, but in small quantities. These nutrients are called as micronutrients and they are equally essential for plants for proper growth, development and disease resistance. Continued use of only common fertilizers, which do not supply these micronutrients, is leading to the micronutrient deficiencies resulting in reduced yields of groundnut.

Essential micronutrients required for groundnut, as in the case of other crops, are:

Iron  Boron  
Zinc  Manganese  
Molybdenum  Copper  
Chlorine  Cobalt  

These micronutrients are to be applied preferably based on soil testing. However, in a standing crop of groundnut, any micronutrient deficiencies can be corrected observing the deficiency symptoms in the crop.
Application of organic manures like well decomposed farm yard manure (FYM) and compost, green manuring and green-leaf manuring practices provide most of the micronutrients to groundnut.
If micronutrient deficiency symptoms are noticed in a standing crop, the following are the sources of micronutrient supplying products.

Iron   Ferrous sulfate (20.1% Fe)  
Boron   Borax (10.5% B) or boric acid  
Zinc   Zinc sulfate (21% Zn) 
Molybdenum  Sodium molybdate (39.7Mo)
ammonium molybdate (54.3% Mo) 
Manganese   Manganese sulfate (16% Mg O)  


  • Groundnut is very susceptible to iron deficiency. Iron deficiency is seen in calcareous and alkaline soils with soil pH above 7.5.
  • Soil application of 25 kg per ha of ferrous sulfate at the final ploughing is recommended in soils low in available iron.

  • Foliar application of 0.5-1.0% ferrous sulfate solution was proved very successful for groundnut if iron deficiency is noticed in a standing crop.



Boron deficiency is usually observed in deep black soils. Boron application need to be carefully done. Even little higher amount of application may result in boron toxicity which reduces groundnut yield. However, the amount of boron recommended on a soil test report improves good kernel development in groundnut.
Application of 10 kg per ha of borax as soil application at final ploughing is recommended for boron deficient soils. Foliar application of 0.25% borax results in overcoming the deficiency of boron in a standing crop. This should be done twice during the cropping season, once at the begining of flower developemnt and once at the pod set stage. Even, foliar application of boron as low as 0.1 ppm also increased the yield.


Zinc deficiency is widespread and groundnut yield is reduced by about half when the zinc level in the soil is lower than 1.2 ppm.
Zinc deficiency is likely to occur

  • when soils are low in organic matter,
  • under high levels of soil P, and
  • when the soils are cool and wet during the vegetative phase.

25 to 50 kg per ha of zinc sulfate applied to the soil at final ploughing is recommended for groundnut.
Unless the soils are very deficient in zinc, zinc application can be practiced once in two years.
If zinc deficiency is observed in a standing crop of groundnut, foliar application of 0.3 to0.5% zinc sulfate solution corrects the problem.


  • The deficiency of molybdenum (Mo) is confined largely to acid soils with pH less than 5. Its deficiency is quite likely in high pH (more than 8) soils also.
    Among the micronutrients, only molybdenum availability decreases with decrease in the soil pH.
  • Soil application of 0.56-1.72 kg per ha of ammonium molybdate and/or foliar spray of 100-200 ppm ammonium molybdate before flowering was found to increase groundnut yield.
  • Micronutrients like Manganese, Magnesium, Copper, Chloride and Cobalt are very rarely deficient in groundnut growing areas.


Your rating: None Average: 3 (1 vote)