Magnesium Sulphate (Epsom Salt)
The quick fix for magnesium deficiency — a soluble magnesium-and-sulphur source that greens up the yellowing between the veins of older leaves.
- Composition
- MgO ~16%, S ~13%
- Form
- Water-soluble crystals
- Price
- Moderate
- Best for
- Magnesium deficiency
Overview
Magnesium sulphate — Epsom salt — supplies about 16% MgO and 13% sulphur, both fully water-soluble. Magnesium sits at the centre of every chlorophyll molecule, so a shortage shows as a distinctive interveinal yellowing: the veins stay green while the tissue between them turns yellow, starting on the older, lower leaves because magnesium is mobile.
The deficiency is common on sandy, acidic and intensively cropped soils, on high-potassium soils (potassium competes with magnesium uptake), and on heavy feeders like banana. A soil application corrects it steadily; a foliar spray gives a fast green-up on a standing crop.
What it is and when to reach for it
- A soluble magnesium-and-sulphur fertiliser — reach for it when older leaves show yellowing between green veins, especially on sandy, acidic or banana/vegetable ground.
- Magnesium is a secondary nutrient, needed in more than micronutrient amounts but less than N-P-K.
- Excess potassium can trigger magnesium deficiency even when soil magnesium is adequate, so balance the two.
How to use it well
- Foliar rescue: spray 1–2% magnesium sulphate (1–2 kg in 100 L water) for a fast green-up of interveinal yellowing; repeat if needed.
- Soil / fertigation: apply as a basal or through the drip where a soil test confirms magnesium deficiency, per the crop’s schedule.
- On strongly acidic soils, dolomitic lime corrects both low pH and low magnesium together and is cheaper for a whole-field fix.
Common mistakes
- Mistaking magnesium deficiency (older leaves, veins stay green) for nitrogen deficiency (older leaves, uniform yellowing) and applying the wrong fertiliser.
- Pushing heavy potassium without watching magnesium, which the potassium then locks out.
- Relying on foliar sprays alone for a severe, whole-field shortage that needs a soil correction.
Organic alternative
Dolomite / FYM
Dolomitic limestone supplies magnesium (and calcium) while raising pH on acidic soils; regular FYM maintains background magnesium.
Crops it is used on
Open a crop for its full nutrient schedule.
Common questions
What are the symptoms of magnesium deficiency?
A distinctive interveinal yellowing — the veins stay green while the leaf tissue between them turns yellow (and later reddish or brown) — starting on the older, lower leaves. It is common on sandy, acidic and high-potassium soils and on heavy feeders like banana.
How do I use Epsom salt on plants?
For a quick correction, spray a 1–2% solution (1–2 kg of magnesium sulphate in 100 litres of water per acre) on the foliage and repeat if the yellowing persists. For a lasting fix, apply it to the soil or through the drip where a soil test confirms the deficiency.
Is magnesium sulphate the same as a micronutrient mix?
No. It supplies only magnesium and sulphur. Magnesium is a secondary nutrient, not a micronutrient like zinc or boron, and is needed in larger amounts. Use magnesium sulphate specifically for magnesium (and sulphur), and a separate product for zinc, boron or iron.
Composition and doses follow ICAR / Soil Health Card guidance; prices are the notified subsidised rates for the season shown and are guidance, not a quote. A soil test for your field always beats a general rate. See our editorial policy.