For optimum plant growth 16 plant nutrients are essential of which N,P,K are macro nutrients which are require in major amounts. These are also called primary nutrients.

All the above macro as well as micro nutrients are equally important and play a vital role in plant growth.

There are equally and essentially needed nutrients in smaller quantities are called micro nutrients and they are also termed as trace elements. They are Boron, copper, iron, manganese, molybdenum, zinc and chlorine.

Next to this there are calcium, magnesium and sulphur which are require for good plant growth, they are called secondary nutrients.

Plant growth regulators or hormones are a separate category of substances and they are not micro nutrients.

Soils contain all nutrients but there reserves are not unlimited. These can be depleted due to continuous cropping, erosion and leaching etc. therefore even fertile soil can not sustain high crop in yields from its own nutrient reserve indefinitely. A deficient soil is a poor handicapped Soil. However nutrient deficiencies can be corrected by the correct application of proper nutrients through manures and fertilizers.

During the past 40 years intensive cropping with high yielding varieties for obtaining higher yields per unit area is done increasingly sought. As cropping intensify and yield level go up, simultaneously the replace and removal of plant nutrients take place through the harvested crops, hence the nutrient deficiencies in soil and crops are in the increase.

Important nutrient that are found to be deficient, in general and needed application are Nitrogen, phosphorous, potassium, sulphur and zinc. In addition to this the deficiencies of magnesium, iron and boron is also in the increase. Hence the balanced fertilizers application to crops must now include all the above nutrients for sustaining normal crop yields. The yield level go down if any such nutrients is found deficient in the soil and not taken care of by integrated manure management.

Micro nutrients which are needed in smaller or minute quantities have certain specific role to play in the plant. These roles range from very simple to highly complex and are fairly specific for a given nutrient one can not take the role of another.

Deficiency of every micro nutrient cause some specific symptom in the plants to attract our attention. If we are careful enough, we can observe the symptoms and find out the nutrient which is responsible for the deficiency symptom and take remedial steps.

Let us analyze the deficiency symptoms Caused by the lack of different micro nutrient in different plants:

Micro-Nutrient Crop or Plant Deficiency
Zinc (21% of Zn) Rice Maize
Citrus Coffee
Soya Bean
Zinc is directly or indirectly required for several enzyme systems, , auxins and in protein synthesis in seed production and maturity. Common symptoms are stunted plant growth, poor tillering, development of light green, yellowish bleached spots, chloritic bands on either side of the midrib in monocots Particularly maize. Brown rusty spots in some crops brown leaves in rice. Small leaves bunch together in fruit crops.
Borax (10.5% of Boron) Grapes Maize
Ground nut
Young leaves are deformed and arranged in the form of a rosette cracking and cork formation of the stalks, stems and fruits. Pre mature fruit drop barren airs in maize hallow heart in ground nut
Copper (24% of Cu) Onion
copper is involved in chlorophyll deficiencies symptom-shoot tips narrow twisted leaves and pale white tips. At . maturity/ears or poorly filled or even empty
Iron (19% of Fe) Cereals
Plays as roles in the synthesis of chlorophyll Carbohydrate production ,cell respiration and N assimilation Deficiency symptoms are similar to Mn. Yellowing of the inter-venial areas of leaves Commonly referred to as iron chlorosis. In severe cases leaves becomes almost pale white due to loss of chlorophyll. In cereals alternate yellow and green stripes along the length of the leaf blade, leaf ball shoots die.
Manganese (30.5% of Mn) Oats
Soya bean
Activate many enzymes and functions as an auto-catalyst. Leaves develop gray lesions but the tip remains green ,base dies, panicle may be empty. Leaves develop chlorotic patches between the veins (resembling Mg deficiency)
Molybdenum (Mo) beans
Involved in enzyme systems particularly nitrate reductase involved in biological nitrogen fixation by bacteria in the root nodules of legumes. Mo deficiency in legumes can resemble N deficiency can cause marginal scorching and rolling or cupping of leaves. Yellow spot disease of citrus and whip tail in cauliflower
Chlorine (Cl) Palms
Oil palm
Involve in the production of oxygen during photosynthesis for raising cell osmotic pressure and in maintaining tissue hydration. Chlorosis in younger leaves and overall wilting.

Careful analysis of soils, crops technical recommendation and symptoms of deficiencies etc are important before going in for application of micro-nutrient to various crops.

Micro Nutrients may be applied based on the recommendation either basal or by foliar application.

Mix no Crop Quantity Recommended Content Method of Application
Zn Mg Mn B Fe Mo Cu
1. Groundnut 5 Kg/ac 4.2% Nil 1.46% 1.57% 3.8% .07% Nil Soil application (Basal) mix with 20 kg of sand and apply before sowing
2. Millets 5 Kg/ac 2.31% Nil 9.15% .52% 5.7% Nil 1% Soil application (Basal) mix with 30 kg of sand and apply before sowing/transplanting.
3. Cotton 5 Kg/ac 3.15% Nil 2.99% 3.15% 3.8% .07% 1.25% Soil application (Basal) mix with 20 kg of sand and apply before sowing
4. Coconut 1 Kg/tree/Yr 5% Nil 4.8% 1.6% 3.8% Nil .5% Soil application (Basal) apply along with FYM.
5. Citrus 1 Kg/10/trees 7.06% Nil 4.2% .6% 2.6% .05% 2% Foliar application 1Kgs/
6. Vegetables 2.5Kg/ac 1.68% Nil 1.22% 2.48% 7.6% .14% 1% soil application mix with (20 kg) before sowing.
7. Pulses 2Kg/ac 4% Nil 6.1% 2.1% 3.8% .35% Nil Soil application mix with sand (20kg) 2nd apply before sowing.
8. sugarcane 1Kg/ac 5.5% 1.3% 1.3% .8% 3% .1% .1% Foliar application at 1% concentration
9. Cotton 1Kg/ac 2.5% 4% 3% .1% 2% .01% .1% Foliar application at 1% concentration.
10. Paddy 1Kg/ac 5% 6% .5% .05% 1% Nil .35% Foliar application at 1% concentration
11. Paddy 10Kg/ac 3% 4% .3% .2% 1.6% Nil .4% Soil application (Basal) mix with 20 kg of sand and apply before planting.
12. Sugarcane 10Kg/acre 6% 1.2% .35% .2% 4.75% Nil .2% Soil application - mix with 20 kg of sand and apply before sowing.
13. Banana 10Kg/ac 4.2% Nil 3.6% 2.1% 3.04% Nil 1% Soil application (Basal) mix with 20 kg of sand and apply before planting.
14. Chilies 1Kg/acre 7.35% Nil 4.58% 2.1% 3.81% Nil 2.5% Foliar application 1Kg/250 lit of water spray, 2 sprays at 20 days interval.