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Exchangeable Mg

Exchangeable Mg is what the soil can hand over. A lab number, not a foliar brand.

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  1. Exchangeable Mg。
  2. Exchangeable Mg is what the soil can hand over. A lab number, not a foliar brand.。
  3. Mg hits old leaves: yellow between green veins, from the bottom up. That is not iron.。
  4. Mg hits old leaves: yellow between green veins, from the bottom up. That is not iron.。

How it appears on the sheet

Mg hits old leaves: yellow between green veins, from the bottom up. That is not iron.

A sketch. Do not fertilise from the picture alone.

Common units

Often cmol/kg or mg/kg.

How to read the number

Mg hits old leaves: yellow between green veins, from the bottom up. That is not iron. Magnesium sits in chlorophyll. High K crowds it out. Sand and high-K vegetable ground show it Easy to mix up: Iron is new leaves; magnesium is old leaves. Wrong leaf position, wrong bag Exchangeable Mg is what the soil can hand over. A lab number, not a foliar brand.。

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

Mg hits old leaves: yellow between green veins, from the bottom up. That is not iron.

Don’t do this

  • Old-leaf striping sprayed as iron.
  • Still pouring potassium that crowds magnesium.
  • Iron is new leaves; magnesium is old leaves. Wrong leaf position, wrong bag.

Lesson video