The subsoiling window: when and how deep
Dry enough to crack, only just below the pan.
- Deep loosening does not smash the layers; ploughing mixes them.
- Opening a ditch is local; deep loosening breaks the hard lid.
- Don’t subsoil every year and scramble raw subsoil; don’t work mud.
- How deep to loosen: About 25–40 cm. Follow where the hard lid sits
- Name what you see before you feed.
- If leaves, roots and the surface disagree, stop.
- A handful that holds then falls apart is the window.
- Depth is just through the pan, often 25–40 cm.
What you see in the field
You meant to subsoil into mud or brick; afterwards, clods, worse seedlings.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 “Ploughing”
Deep loosening does not smash the layers; ploughing mixes them.
Looks like “Opening a ditch”
Opening a ditch is local; deep loosening breaks the hard lid.
Do this / don’t do that
- 1You meant to subsoil into mud or brick; afterwards, clods, worse seedlings. Compare the worst plants with a neighbour ridge before you add a bag, or the next step will chase the wrong thing.
- 2Crumb-moist, alternate years, just through the pan. Organic matter and cover after. Ask whether the machine rips or inverts.
- 3Don’t subsoil every year and scramble raw subsoil. 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 subsoil every year and scramble raw subsoil; don’t work mud.
Rate range
How deep to loosen
About 25–40 cm
Follow where the hard lid sits.
Interval
Mostly every other year
Loosening every year is not needed.
These are ranges. Confirm with your local extension station and the product label.
When you see You meant to subsoil into mud or brick; afterwards, test. Walk an S and mix — one hole is not the field.
Lesson video
2026-03-01 · 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