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Green manure: it can feed the soil and also smother the next crop

Turn it in with time to rot, not the week you plant.

Thin organic matter
Speed
  1. Fresh herbage in, seedlings yellow, soil hot.
  2. Worse if late and thick.
  3. Green manure stealing nitrogen is one kind of nitrogen shortage — microbes eat first.
  4. A thick fresh-green layer can rot in spots; disease spreads.
  5. Don’t sow thick on freshly turned green; don’t skip the nitrogen IOU.
  6. When to turn it in: Mostly around full bloom. Too late, the stems lignify and won’t rot
  7. Name what you see before you feed.
  8. If leaves, roots and the surface disagree, stop.

What you see in the field

Fresh herbage in, seedlings yellow, soil hot. Worse if late and thick.Rub a handful next to a darker neighbour that still forms crumbs. Pale dusty soil that leaks after rain matches this page. Yellow leaves are extra — first ask whether the soil still has body.

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 “Nitrogen shortage”

    Green manure stealing nitrogen is one kind of nitrogen shortage — microbes eat first.

  • Looks like “Disease”

    A thick fresh-green layer can rot in spots; disease spreads.

Do this / don’t do that

  1. 1Fresh herbage in, seedlings yellow, soil hot. Worse if late and thick. Compare the worst plants with a neighbour ridge before you add a bag, or the next step will chase the wrong thing.
  2. 2Turn around flowering, spread even, wait, a few kg N/mu class locally. Don’t smother seed under a thick wet blanket.
  3. 3Don’t sow thick on freshly turned green. 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 sow thick on freshly turned green; don’t skip the nitrogen IOU.

Rate range

When to turn it in

Mostly around full bloom

Too late, the stems lignify and won’t rot.

Add nitrogen

A few kg urea per mu

Follow the fresh-green amount and the station.

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

Organic matter

Whether the green manure left meat

Only clear after several years.

When you see Fresh herbage in, test. Mix several spots of the tilled layer; skip the edge and the manure heap.

Lesson video

2026-03-09 · 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