Indian Economy · IndEco0086
Micronutrients in Plants and Indian Soils
Micronutrients are plant nutrients needed in very small amounts. Small does not mean optional. A plant still needs each one to finish its life cycle, and no other nutrient can fully take over its job.
At a Glance
- Eight micronutrients are widely accepted: iron, manganese, zinc, copper, boron, molybdenum, chlorine, and nickel.
- An ICAR study of 8,287 samples from 600 districts (2014-20) found 36.5% low in zinc and 23.4% low in boron.
- High soil pH can block zinc and iron uptake even when the soil actually contains them.
- The Soil Health Card tests only five of the eight micronutrients, alongside N, P, K, sulphur, pH, salts, and organic carbon.
- Micronutrient
- A plant nutrient needed in tiny amounts but still essential.
- Macronutrient
- A plant nutrient needed in much larger amounts, such as N, P, and K.
- Essential nutrient
- One a plant cannot complete its life cycle without, with its own direct role.
- Chelate
- A form that holds a metal nutrient so roots can use it, even in tricky soil.
- Soil Health Card
- A government report card of 12 soil measures for a farmer’s field.
- Foliar spray
- A nutrient spray applied to leaves rather than the soil.
Contents
Nutrient Groups
Primary macronutrients
Nitrogen (N), phosphorus (P), and potassium (K), needed in large amounts. Fertiliser bags often show these three.
Secondary macronutrients
Calcium, magnesium, and sulphur, also needed in larger amounts than micronutrients.
Micronutrients
Only traces of the eight are needed. Too little or too much can still harm growth.
Air and water
Carbon, hydrogen, and oxygen, drawn mainly from air and water. These are essential too.
A nutrient is essential if a plant cannot complete its life cycle without it, and it must have its own direct role. Another element cannot simply do the same job.
QUICK CHECK 1 OF 8 · TRUE OR FALSE
Plants need eight accepted essential micronutrients, including nickel.
True. The eight are iron, manganese, zinc, copper, boron, molybdenum, chlorine, and nickel.
Eight Micronutrients
Must Know
Use this table for clues, not a final field diagnosis. Symptoms differ by crop and growth stage.
| Nutrient | Main job | Possible clue when short |
|---|---|---|
| Iron (Fe) | Helps energy transfer and green colour formation. | New leaves may turn yellow between green veins. |
| Manganese (Mn) | Helps photosynthesis and enzymes. | Newer leaves may show pale patches. |
| Zinc (Zn) | Helps enzymes and growth control. | Small leaves or short gaps between leaves may appear. |
| Copper (Cu) | Helps enzymes and normal growth. | Young shoots may weaken or die back. |
| Boron (B) | Helps cell walls and flower or fruit growth. | Growing tips or fruit set may suffer. |
| Molybdenum (Mo) | Helps plants use nitrate; it also aids nitrogen fixation. | Plants may look like they lack nitrogen. |
| Chlorine (Cl) | Helps water balance and photosynthesis. | Deficiency is rare in field soils. |
| Nickel (Ni) | Helps break down urea inside plants. | Deficiency is uncommon on farms. |
Remember: iron moves poorly inside the plant, so its shortage often shows on new leaves first. A mobile nutrient can move from old leaves, so its shortage may show there first instead. This is a clue, not a verdict.
QUICK CHECK 2 OF 8 · TRUE OR FALSE
Zinc and boron were common gaps in a large Indian soil sample study.
True. ICAR reported low available zinc in 36.5% and boron in 23.4% of 8,287 samples collected during 2014-20.
Indian Soils
Good to Know
Some soils contain a nutrient but keep it in a form roots cannot take up. High soil pH, a more alkaline soil, can make zinc and iron harder to use. Low organic matter can add to the problem.
Acidic soils have other limits. Molybdenum may become less available, and boron may wash out of sandy soils. Waterlogging can starve roots of air and change nutrient chemistry. Too much soluble iron can even become toxic in wet soils.
Indian example: ICAR analysed 8,287 surface soil samples from 600 districts during 2014-20. About 36.5% were low in available zinc, and about 23.4% were low in available boron. Those are sample shares, not a diagnosis of every Indian field.
In Punjab rice fields, scientists linked zinc shortage to high pH, calcium carbonate, and excess phosphorus. An iron problem can also occur in light, high-pH soil. The same farm may face different limits in different seasons.
More fertiliser is not always better. Too much phosphorus can worsen zinc shortage, and too much boron can harm plants. Test and balance the dose.
QUICK CHECK 3 OF 8 · TRUE OR FALSE
Nickel is not an essential plant micronutrient.
False. Nickel is essential in tiny amounts. It helps the enzyme that breaks down urea.
QUICK CHECK 4 OF 8 · TRUE OR FALSE
Iron shortage can make new leaves yellow between their veins.
True. Iron moves poorly from old leaves to new ones. Yet yellowing can have other causes.
Test and Correct
Great to Know
First, look at which leaves and field patches show trouble. Then check water, pests, roots, and soil pH. Use soil and, when useful, leaf tests. Finally, use a crop-specific dose and test again.
The Soil Health Card reports 12 soil measures: N, P, K, sulphur, five micronutrients, pH, electrical conductivity, and organic carbon. Electrical conductivity is a clue to soluble salts, and organic carbon helps describe soil organic matter.
A leaf test shows what the plant actually took up. Test a troubled patch and a healthy patch of the same crop. Also check roots, water stress, and disease, since yellow leaves can have many causes.
Soil application
Put the recommended zinc, boron, or other input in the soil, matching form and dose to the soil test.
Leaf spray
A foliar spray can supply a nutrient through leaves quickly, but it may not fix the root cause.
Chelated form
A chelate holds some metal nutrients in a usable form. It can help where high pH blocks uptake.
Organic matter
Compost or manure can improve soil structure and nutrient cycling. It does not replace a needed test.
Ask a local agricultural adviser for the product and dose. Crop, soil, weather, and growth stage all matter. Do not copy a spray rate from another crop.
QUICK CHECK 5 OF 8 · TRUE OR FALSE
A yellow leaf alone proves that the soil lacks zinc.
False. Many problems can yellow leaves. Check the crop, field pattern, soil, water, and test results.
QUICK CHECK 6 OF 8 · TRUE OR FALSE
The Soil Health Card reports 12 soil measures, including five micronutrients.
True. The five are zinc, iron, copper, manganese, and boron. It also covers N, P, K, S, pH, salts, and organic carbon.
Exam Points
- Micronutrients are essential, but needed only in traces.
- Nickel belongs on the modern list of eight. Older lists may name seven.
- N, P, and K are primary macronutrients. Calcium, magnesium, and sulphur are secondary ones.
- High pH can block iron and zinc uptake even when soil contains them.
- Young-leaf yellowing suggests iron, but it does not prove it.
- The Soil Health Card tests five micronutrients, not all eight.
QUICK CHECK 7 OF 8 · TRUE OR FALSE
Nitrogen, phosphorus, and potassium are micronutrients.
False. They are primary macronutrients. Plants need them in larger amounts.
Current Examples
Current Affairs
In a 2026 mango-orchard programme, ICAR experts stressed zinc, iron, and boron management, and also advised soil tests before fertiliser. A separate ICAR mandarin study tested tailored micronutrient mixes rather than one blanket recipe.
These stories show a rule: correct the field’s real limit. A nutrient mix is useful only when the crop and soil actually need it.
See the ICAR Indian soil sample study, 2014-20, the ICAR note on zinc and iron problems in Punjab rice, and the Agriculture Ministry note on the Soil Health Card’s 12 measures.
QUICK CHECK 8 OF 8 · TRUE OR FALSE
Too much boron can injure plants, even though plants need a little boron.
True. The useful range can be narrow. Apply a tested dose for the crop and soil.
MCQ on Micronutrients in Plants and Soils
Try 6 practice questions on micronutrients and Indian soils.
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