The plough pan: a lid under the rotary tiller
The hoe works the top, roots hit a floor.
- A shiny hard layer below 15–20 cm; roots turn.
- The top ponds after rain.
- The whole layer hard is packing; the plough pan is the strip underneath.
- Some fields have a parent-material clay pan. How deep to loosen follows the local advice.
- Don’t fluff 15 cm and pack it again; keep heavy traffic off wet soil.
- How deep to loosen: Usually 25–40 cm. Follow the profile. Don’t turn raw subsoil every year
- Name what you see before you feed.
- If leaves, roots and the surface disagree, stop.
What you see in the field
A shiny hard layer below 15–20 cm; roots turn. The top ponds after rain.When a hoe bounces or footprints sink, dig twenty centimetres and look for a shiny hard pan. Roots that turn sideways count. Cracked dust is extra. Keep machines off wet soil.
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 whole layer packed hard”
The whole layer hard is packing; the plough pan is the strip underneath.
Looks like “A natural clay pan”
Some fields have a parent-material clay pan. How deep to loosen follows the local advice.
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 fluff 15 cm and pack it again; keep heavy traffic off wet soil.
Rate range
How deep to loosen
Usually 25–40 cm
Follow the profile. Don’t turn raw subsoil every year.
Rotted manure
1–2 t per mu
After loosening there must be meat, or it packs again.
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 A shiny hard layer below 15–20 cm; roots turn. The top ponds after rain, test. Take soil from the bad patch and from a greener neighbour, separately.
Lesson video
2026-04-22 · 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