Calcareous soil: the fertiliser is in the ground, the root can’t eat it
High pH locks iron, zinc and phosphorus.
- The sheet can show low available iron, phosphorus or zinc while the total is not low.
- Nitrogen shortage yellows old leaves; calcareous soil often yellows new leaves.
- Don’t dump ferrous sulphate on high pH; don’t treat every yellow as nitrogen.
- Foliar chelated iron: Follow the pack. First aid, repeat a few times
- Name what you see before you feed.
- If leaves, roots and the surface disagree, stop.
What you see in the field
The soil is not poor, yet leaves yellow — especially new leaves with green veins. pH often above 7.5.Squat on the whitest, worst strip and scrape the crust. Compare with a neighbour that is still green. White crust plus scorched margins count; wilt without a crust may just be drought. Note whether the ditch actually runs.
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 “The soil really has no fertiliser”
The sheet can show low available iron, phosphorus or zinc while the total is not low.
Looks like “Nitrogen shortage”
Nitrogen shortage yellows old leaves; calcareous soil often yellows new leaves.
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 dump ferrous sulphate on high pH; don’t treat every yellow as nitrogen.
Rate range
Foliar chelated iron
Follow the pack
First aid, repeat a few times.
Organic manure
Follow local advice
Steadier than dumping iron salts.
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 The soil is not poor, test. If the leaf and the soil disagree, test before you pour.
Lesson video
2026-03-26 · 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