Fertiliser burn and over-fertilisation: the damage that looks like hunger
Quick answer
Fertilisers are salts. Applied heavily, close to the stem, or onto dry soil, they raise the salt concentration around the roots so far that water is drawn out of the root instead of into it. The plant wilts in moist soil and does not respond to watering. Because that looks like hunger, the common response is to feed again — which is what turns recoverable damage into a dead plant. If damage followed a recent feeding, do not add more.
How to recognise it
- Timing. Decline begins within days of an application.
- Distribution. Damage has sharp edges matching where the product was placed — a ring at the stem, a band along a line, a patch.
- Wilting that water does not fix. This separates it from thirst.
- A white salt crust on the surface or at the edge of the drip wetting pattern.
Specific excesses FAO documents
- Phosphorus: extremely high levels produce a watery edge on the leaf tissue which becomes necrotic; in very severe cases this can kill the plant.
- Ammonium: high ammonium in solution can be toxic, particularly where the solution is alkaline, because ammonia diffuses through plant membranes and interferes with metabolism.
- Copper: excess copper induces iron deficiency, so chlorosis is a common symptom — an excess of one element producing the appearance of another's shortage.
- Boron: toxicity arises where irrigation water carries more than 1–2 ppm, producing tip yellowing then necrosis of tip and margins.
- Nitrogen: excess prolongs the vegetative period and delays maturity.
The delayed version
Fertiliser burn is root injury. An injured root absorbs poorly, so symptoms that look nutritional — yellowing, stunting — can appear weeks after the original event, by which time the feeding has been forgotten and the decline is blamed on a shortage.
If you suspect it
- Stop feeding. Nothing else matters until that is settled.
- Establish the timeline. What was applied, where exactly, how much, and was it watered in?
- Check the distribution against where the product went.
- Look for a salt crust at the surface and at the wetting edge.
- Get an ECe measurement from the root zone, compared against soil outside it.
- Treat it as a site problem — the direction of remedy is leaching and drainage, not addition — and get a specialist to assess it.
In Kuwait's conditions
The risk is higher here, not lower. FAO lists an occasional excess of soluble salts among the problems of arid soils, so a fertiliser application may be adding salt to soil that already carries a load. Summer maxima of 42–46°C mean the plant is already stressed and less able to tolerate any additional burden, and an interruption of irrigation immediately after feeding is among the most dangerous combinations.
General arid-region guidance, not a Kuwait measurement.
Common mistakes
- Responding to the symptoms by feeding again. This is the mistake that kills.
- Applying fertiliser to dry soil and not watering it in.
- Placing granular product hard against the stem or trunk.
- Using un-decomposed manure close to roots.
- Assuming an organic material cannot burn.
Boundary
The remedy here is directional only — leaching and improving drainage rather than addition. No leaching volume, flushing schedule, amendment or product is given, because those depend on the measured severity, your soil and your drainage, and need a site assessment. On established trees or severe cases, an on-site inspection is necessary.
Related glossary terms
Sources
- FAO — Fertilizer and Plant Nutrition Bulletin 16, Chapters 3 and 4.
- FAO — Soils Portal: Salt-affected soils.
- Kuwait Meteorological Department — Climate.
All accessed 26 August 2026. Last reviewed: 27 August 2026.