Southern paddy nutrients: the reduced layer locks what you applied
Black mud is not a warehouse you can keep stacking.
- Southern paddies, yellow seedlings, cold water.
- Long deep water: iron and manganese rise, nutrients lock in the reduced layer.
- A reducing layer lies about availability. Read the water layer and the roots first.
- Nitrogen shortage: white roots. A reducing fault: smelly roots.
- Don’t keep deep water and pour nitrogen; don’t double compound on black roots.
- The water layer: Shallow-wet, and dry it if you can. Follow the growth stage
- Name what you see before you feed.
- If leaves, roots and the surface disagree, stop.
What you see in the field
Southern paddies, yellow seedlings, cold water. Long deep water: iron and manganese rise, nutrients lock in the reduced layer.Walk the worst strip and compare a neighbour. Photograph the whole plant, a close-up and the soil surface. If those three do not line up, do not rush a bag. Lab numbers have to match the field.
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 “Phosphorus or zinc shortage alone”
A reducing layer lies about availability. Read the water layer and the roots first.
Looks like “Nitrogen shortage”
Nitrogen shortage: white roots. A reducing fault: smelly roots.
Do this / don’t do that
- 1Southern paddies, yellow seedlings, cold water. Long deep water: iron and manganese rise, nutrients lock in the reduced layer.
- 2Drain and expose. Read roots and water. If acid, follow the acid guide. Thin feed after new roots. Rotted organic matter, not fresh herbage steeped deep.
- 3Don’t keep deep water and pour nitrogen. 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 keep deep water and pour nitrogen; don’t double compound on black roots.
Rate range
The water layer
Shallow-wet, and dry it if you can
Follow the growth stage
Phosphorus / zinc
Band it, follow a soil test
Air first, then a feed.
These are ranges. Confirm with your local extension station and the product label.
Paddy numbers must be read with the water layer
Don’t lock a dry-land number onto a paddy.
When you see Southern paddies, test. Write the field and the date on the bag.
Lesson video
2026-03-03 · 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