Skip to content

Back to Reading the soil test

Phosphorus (P)

Phosphorus is roots and flowering. The word is P; the field job is purple seedlings and pH.

Speed
  1. Phosphorus (P)。
  2. Phosphorus is roots and flowering. The word is P;。
  3. the field job is purple seedlings and pH.。
  4. Deficiency: purple, stunted seedlings, few roots. Warmth does not restart them.。
  5. Deficiency: purple, stunted seedlings, few roots. Warmth does not restart them.。

How it appears on the sheet

Deficiency: purple, stunted seedlings, few roots. Warmth does not restart them.

A sketch. Do not fertilise from the picture alone.

Common units

Total P often g/kg. Available P is what the root can touch.

How to read the number

Deficiency: purple, stunted seedlings, few roots. Warmth does not restart them. Acid soils nail it with Fe/Al; calcareous soils nail it with calcium. The soil has P; the root cannot touch it Easy to mix up: N is even yellow; P is dark green with purple. High P also blocks zinc Phosphorus is roots and flowering. The word is P; the field job is purple seedlings and pH.。

Thresholds only, not a prescription. Rates live in the field guide. This page does not hand you a bag count.

What it looks like in the field

Deficiency: purple, stunted seedlings, few roots. Warmth does not restart them.

Don’t do this

  • Dumping phosphate on acid soil the root cannot touch.
  • Purple seedlings chased with nitrogen.
  • N is even yellow; P is dark green with purple. High P also blocks zinc.

Lesson video