Ammonia burn: the dressing fumes the leaves the same day
Urea or ammonium on wet heat can gas the crop.
- Salt injury has white crust; ammonia injury has a smell and a just-applied history.
- Spray injury has a spray history; ammonia injury has a fertiliser history and a smell.
- Don’t shut the house and pour ammonia fertiliser; don’t feed again while it still stings the nose.
- Ventilation: Open the vents at once. The first job
- Name what you see before you feed.
- If leaves, roots and the surface disagree, stop.
- Raw manure, ammonium bicarbonate, or surface urea in the wet sends ammonia up.
- A closed house traps it.
What you see in the field
Leaf margins look smoked inside a house, right after fertiliser, worst on young leaves, ammonia smell.Ask what was applied, and how much. Injury in a line with granules in the seed furrow matches this page. Scattered patches look more like disease. Do not stack another bag.
Tap to enlarge. The caption says what to photograph. Missing field photos are marked as to-be-added.
Why it looks like this
The field looks like this because the root cannot take water or nutrients the usual way. Fix the soil condition first — drainage, salt, acidity, compaction or a salt of fertiliser — then a thin feed. Rates live in the range on this page; confirm with a local station and the label.
Easy to mix up
Looks like “Salt injury”
Salt injury has white crust; ammonia injury has a smell and a just-applied history.
Looks like “Spray injury”
Spray injury has a spray history; ammonia injury has a fertiliser history and a smell.
Do this / don’t do that
- 1Leaf margins look smoked inside a house, right after fertiliser, worst on young leaves, ammonia smell.
- 2Vent first. Skip this feed. Only rotted manure indoors. Don’t surface-apply ammonium bicarbonate in a shut house.
- 3Don’t shut the house and pour ammonia fertiliser. Use the range on this page only as a range. Confirm with a local station and the product label.
Don’t do this first
- Don’t shut the house and pour ammonia fertiliser; don’t feed again while it still stings the nose.
Rate range
Ventilation
Open the vents at once
The first job.
Urea
Deep, cover with soil, follow the label
In a house, don’t close up after a surface dressing.
These are ranges. Confirm with your local extension station and the product label.
How soon after a spray or a feed it showed
A 1–3 day burst looks more like spray injury / fertiliser burn.
When you see Leaf margins look smoked inside a house, test. Mix several spots of the tilled layer; skip the edge and the manure heap.
Lesson video
2026-03-19 · Li Zeyu · For learning. Serious damage: local agronomist or a soil test.
For learning only. Fertiliser and pesticide decisions need a local agronomist and a soil test.
Not sure? Photograph the field to identify the problem