Paddy reduction: black, smelly roots, no new white tips
No air in the mud. Fertiliser can’t fix a drowned root.
- A shortage does not make roots smell; a reducing fault does.
- They often arrive together. Drain both.
- Don’t double fertiliser on black roots; don’t skip aeration year after year.
- Dry the field: Follow the growth stage. Stop when the surface hair-cracks and roots are white. Follow the station
- Name what you see before you feed.
- If leaves, roots and the surface disagree, stop.
- No oxygen, manganese iron and sulphur reduce, roots are poisoned.
- Not a missing bag of compound.
What you see in the field
Long deep water, soil smells, roots black with no new white tips, sometimes a hydrogen-sulphide smell.Is the soil wet or dry, the root white or black? Wet wilt and a foul root mean drain first. Leaf wilt with white roots may be drought. Smell the root before you irrigate.
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 “Ordinary shortage”
A shortage does not make roots smell; a reducing fault does.
Looks like “Ferrous toxicity”
They often arrive together. Drain both.
Do this / don’t do that
- 1Compare the worst plants with a neighbour ridge. Photograph whole plant, close-up and soil surface before you add fertiliser.
- 2Match roots, leaves and the soil surface to this guide. If they do not line up, do not copy a bag count.
- 3Use the rate range on this page only as a range. Confirm with a local station and the product label.
Don’t do this first
- Don’t double fertiliser on black roots; don’t skip aeration year after year.
Rate range
Dry the field
Follow the growth stage
Stop when the surface hair-cracks and roots are white. Follow the station.
Straw
Enough, and chopped
See the straw-return guide.
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 Long deep water, test. If the leaf and the soil disagree, test before you pour.
Lesson video
2026-03-15 · 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