Bentonite Sulphur (~90% S)
The concentrated sulphur fertiliser — 90% sulphur in a spreadable granule that releases through the season for oilseeds and pulses.
- Composition
- ~90% elemental S
- Form
- Bentonite clay granules
- Price
- Moderate
- Best for
- Sulphur for oilseeds & pulses
Overview
Bentonite sulphur is elemental sulphur (about 90%) bound into bentonite clay granules. In the soil the granules take up moisture and swell, breaking apart so soil bacteria can slowly oxidise the sulphur into the sulphate form plants use. That slow release feeds sulphur across the season, which suits the long sulphur demand of oilseeds and pulses.
Its high concentration means you spread far less material than with gypsum or SSP for the same sulphur — a real saving on transport and labour. As the sulphur oxidises it also mildly acidifies the soil, which can help on alkaline soils but should be watched on already-acidic ground.
What it is and when to reach for it
- A concentrated, slow-release sulphur fertiliser — reach for it to cover the sulphur requirement of mustard, groundnut, soybean and other oilseeds and pulses.
- It carries no N-P-K, so it complements, not replaces, your main nutrition.
- The slow oxidation means it should go in a little ahead of the crop’s peak sulphur demand, not as a last-minute rescue.
How to use it well
- Apply about 8–10 kg/acre as a basal at or before sowing, incorporated into moist soil so the granules can break down.
- Because it releases slowly, apply it in time — it is a season-long feed, not a quick correction like a sulphate spray.
- On alkaline soils its mild acidifying effect is a bonus; on acidic soils, prefer gypsum, which supplies sulphur without lowering pH.
Common mistakes
- Expecting an instant effect — elemental sulphur must be oxidised by soil bacteria first, which takes time and warmth.
- Applying it to a standing crop already showing acute sulphur deficiency, where a quick sulphate source works faster.
- Adding it to already-acidic soil without checking pH, since it acidifies further.
Organic alternative
Gypsum
Gypsum is a permitted mineral that supplies readily-available sulphate sulphur (and calcium) without the delay of elemental sulphur or its acidifying effect.
Crops it is used on
Open a crop for its full nutrient schedule.
Common questions
Bentonite sulphur or gypsum for sulphur?
Bentonite sulphur is far more concentrated (~90% S vs ~18% in gypsum), so you spread much less, and its slow release feeds sulphur across the season — but it must be oxidised by soil bacteria first, so apply it ahead of time. Gypsum gives immediate sulphate sulphur plus calcium and does not acidify the soil, which is better on acidic ground or for a quicker effect.
How much bentonite sulphur per acre?
For oilseeds and pulses, roughly 8–10 kg per acre as a basal at or before sowing, incorporated into moist soil. Because it releases slowly, timing matters more than a large one-off dose.
Does bentonite sulphur lower soil pH?
Yes, mildly. As soil bacteria oxidise the elemental sulphur they produce acidity, which is useful for reclaiming alkaline soils but a reason for caution on soils that are already acidic — check the pH before repeated use.
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.