Recognising nutrient deficiency — and what else looks identical
Quick answer
Start with one question: is the symptom on the oldest leaves or the newest? A nutrient that can move inside the plant is withdrawn from old leaves to feed new growth, so its shortage shows at the bottom. One that cannot move strands the new growth, so it shows at the top. That single question halves the list. Then rule out salinity, irrigation faults, root damage and pests — all of which look the same. A visual symptom alone is not a confirmed diagnosis.
Position first
| Where it shows | Nutrients | Why |
|---|---|---|
| Older leaves | N, P, K, Mg (Mo in the middle) | Mobile in the phloem — moved out of old leaves to save new growth |
| Younger leaves | Fe, Mn, S, Zn | Immobile — cannot be relayed from old leaves |
| Growing points | Ca, B, Cu | Immobile, and the growing tip is what fails first |
Then appearance
- General yellowing, lower leaves: nitrogen is the usual candidate.
- General paleness, upper leaves, persisting after nitrogen: points to sulphur instead.
- Interveinal yellowing, veins staying green: magnesium on old leaves; iron or manganese on new ones. Iron and manganese cannot be separated by eye.
- Margin yellowing then scorch, moving inwards, old leaves: potassium — but salt injury looks the same.
- Distorted, cupped or dying new growth: calcium or boron — but mites look the same.
- Small leaves in a rosette, short internodes: zinc.
The four look-alikes, every time
FAO is explicit: chlorotic and necrotic leaves might also result from the toxic effects of nutrients, pollution, and disease and insect attack, and confirmation of the cause is important before corrective measures are taken.
- Salinity — paleness, stunting, margin scorch. Needs an ECe measurement.
- Irrigation — both too little and too much produce wilting and yellowing. Check the soil at root depth, and check the emitter actually runs.
- Root damage — a full soil and a starving plant. Inspect planting depth and root condition.
- Pests and disease — usually asymmetric or patchy, and often spreading to neighbours.
A working sequence
- Where on the plant is the oldest symptom, and where is the newest?
- Is the new growth sound? If not, you are in a different pattern entirely.
- Check the soil at root depth and confirm the irrigation is running.
- Compare with neighbouring plants of the same kind. One plant → its roots or emitter. A whole area → soil, water or salinity.
- Photograph with a date and compare a week later: advancing or static?
- Get a soil and water analysis before buying anything.
In Kuwait's conditions
On alkaline calcareous soil, iron and zinc deficiency are the frequent ones, through fixation under alkaline reaction — meaning the element is present but unavailable. So interveinal yellowing on young leaves here is an expected pattern with a known explanation, and the answer is usually not more iron in the soil.
Equally, margin scorch is as likely to be salt injury as potassium shortage, and the two corrections are opposite.
Common mistakes
- Diagnosing from a photograph of one leaf instead of the whole plant.
- Concluding the soil lacks iron because the leaves show iron symptoms.
- Reading margin scorch as potassium without measuring salinity.
- Treating stunting as a nutrient symptom — almost every shortage produces it, so it identifies nothing alone.
- Feeding before checking irrigation and roots.
The boundary
A visual symptom alone is not a confirmed diagnosis. This guide narrows possibilities; it does not reach verdicts. Confirmation needs a soil analysis with pH and ECe, a water analysis, and tissue analysis where a specific element must be identified. No treatment, product or rate is given here.
Related glossary terms
Sources
- FAO — Fertilizer and Plant Nutrition Bulletin 16, Chapters 3 and 4.
- FAO — Soils Portal: Salt-affected soils.
All accessed 26 August 2026. Last reviewed: 27 August 2026.