Red-yellow earth: test pH before you consider lime
Southern red soil is acid by nature. Don’t copy a northern lime bill.
- Nitrogen shortage: old leaves even yellow, roots still white. Acid soil hurts the roots first and the whole plant stalls.
- Still stalled after a warm spell, and pH is low — that is not chill alone.
- Don’t copy a northern wheat lime rate; don’t use grain rates on tea.
- Agricultural lime: 50–150 kg per mu, twice. Follow a soil test and the texture. Better too little than too much
- Name what you see before you feed.
- If leaves, roots and the surface disagree, stop.
- The soil is already acid; rain strips bases.
- Lime is medicine, not a meal.
What you see in the field
On red-yellow earth, stunted yellow plants with brown tips — read colour and roots, then pH.Walk the worst strip. Pull one plant, rinse the roots at the ditch without rubbing the tips, and read white tips versus brown bald ones. A rusty film on water is extra, not required. Grain land and tea do not share a pH target.
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 “Nitrogen shortage”
Nitrogen shortage: old leaves even yellow, roots still white. Acid soil hurts the roots first and the whole plant stalls.
Looks like “Chill-stunted seedlings”
Still stalled after a warm spell, and pH is low — that is not chill alone.
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 copy a northern wheat lime rate; don’t use grain rates on tea.
Rate range
Agricultural lime
50–150 kg per mu, twice
Follow a soil test and the texture. Better too little than too much.
Rotted manure
1–2 t per mu
Build the buffer first.
These are ranges. Confirm with your local extension station and the product label.
When acid frees aluminium, it bites the root
Only when it is too acid does it show.
When you see On red-yellow earth, test. If the leaf and the soil disagree, test before you pour.
Lesson video
2026-03-13 · 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