Recognising Magnesium Deficiency in Crops

Magnesium deficiency is easy to miss early and expensive to ignore. Knowing what it looks like helps distributors and agronomists recommend the right correction.

The classic symptom

Magnesium is mobile inside the plant. When supply runs short, the plant moves magnesium from older leaves to new growth, so symptoms appear first on older, lower leaves. The typical pattern is interveinal chlorosis: the tissue between the veins turns yellow while the veins stay green. In some crops the yellow areas later turn reddish, purple or brown.

Conditions that make it likely

• Sandy or light soils that leach easily.
• Acidic soils.
• High potassium or ammonium levels, which compete with magnesium uptake.
• Heavy rainfall or over-irrigation.
• High-yielding crops that remove a lot of magnesium each season.

Confirming it

Visual symptoms can be confused with other deficiencies or with disease, so soil tests and leaf tissue analysis are the reliable way to confirm a magnesium problem. Tissue tests also show whether a correction has worked.

Correcting it

Foliar sprays of magnesium sulphate give a fast, short-term response. Soil or fertigation applications build up supply for the rest of the season. Rates should follow soil test results and local agronomic advice.

For distributors

If your market has sandy soils, high-potassium fertilizer use or intensive horticulture, magnesium sulphate is usually a steady seller. We supply both heptahydrate for fertigation and monohydrate for blending, so you can cover both customer types from one source.