Skip to content
Tuzhi
中文Sign in

Back to the field guide

Physiological acid fertilisers make the soil more acid year after year

Ammonium-N is a bill the soil pays in pH.

Acid soil
Speed
  1. A high-yield field slowly stalls; pH walks down year after year.
  2. Read the last years of N and K bags.
  3. Parent-material acid and fertiliser-made acid stack. Read the fertiliser book.
  4. Salt injury has white crust; acidifying is pH creeping down.
  5. Don’t lime to offset a foolish nitrogen habit; don’t add N every year without a pH.
  6. Rotate the nitrogen source: Don’t lean on one ammonium nitrogen year after year. Follow the local agronomist
  7. Name what you see before you feed.
  8. If leaves, roots and the surface disagree, stop.

What you see in the field

A high-yield field slowly stalls; pH walks down year after year. Read the last years of N and K bags.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.

A sketch. Do not fertilise from the picture alone.

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 field’s own red-yellow acid”

    Parent-material acid and fertiliser-made acid stack. Read the fertiliser book.

  • Looks like “Salt injury”

    Salt injury has white crust; acidifying is pH creeping down.

Do this / don’t do that

  1. 1A high-yield field slowly stalls; pH walks down year after year. Read the last years of N and K bags.
  2. 2Rotate N forms, add rotted organic matter. If too acid, follow the acid guide. Don’t lime every year to cancel acid-forming fertiliser.
  3. 3Don’t lime to offset a foolish nitrogen habit. 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 lime to offset a foolish nitrogen habit; don’t add N every year without a pH.

Rate range

Rotate the nitrogen source

Don’t lean on one ammonium nitrogen year after year

Follow the local agronomist

Watch pH

At least once in two years

High-nitrogen fields need it more often.

These are ranges. Confirm with your local extension station and the product label.

pH

Whether acidifying is happening

Falling year after year: stop.

When you see A high-yield field slowly stalls; pH walks down year after year. Read the last years of N and K bags, test. Mix several spots of the tilled layer; skip the edge and the manure heap.

Lesson video

2026-03-06 · 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