Ammonium Sulphate (20.6% N, 24% S)
Two nutrients in one bag — steady nitrogen and a large helping of sulphur. Excellent on alkaline soils and sulphur-hungry crops; use with care on acidic ones.
- Composition
- 20.6% N, 24% Sulphur
- Form
- White / off-white crystals
- Price
- Moderate (low N %, so bulkier)
- Best for
- Sulphur + N; tea, potato, paddy, oilseeds
Overview
Ammonium sulphate carries about 20.6% nitrogen and 24% sulphur. Its nitrogen percentage is low, so you carry more bags than with urea, but the sulphur is the real draw: it is one of the cheapest ways to correct the sulphur deficiency that is now widespread across Indian soils, especially for oilseeds, tea and potato.
It is strongly acidifying — which is a benefit on alkaline and sodic soils but a drawback on acidic ones, where it can push the pH down further and needs to be balanced with lime. Tea gardens, which grow on acidic soils but want that acidity, and crops like potato and paddy where its form of nitrogen and its sulphur both help, are its classic homes.
What it is and when to reach for it
- A dual nitrogen-and-sulphur fertiliser — reach for it when the crop needs sulphur as well as nitrogen, or on alkaline soils that benefit from acidification.
- Its low nitrogen content means more bags per acre than urea, so factor in transport and handling.
- It is a mainstay in tea and a strong choice for potato and paddy.
How to apply it well
- Use it as the nitrogen source where sulphur is also short — it covers both in one application.
- On alkaline or sodic soils its acidifying effect is a bonus; apply as basal or as an early top dressing.
- For oilseeds, it is a simple way to add sulphur at the same time as nitrogen.
Common mistakes
- Using it heavily on already-acidic soils without lime, driving the pH down and hurting the crop.
- Comparing its price to urea on nitrogen alone — its value is the sulphur it also supplies.
- Assuming it is a complete fertiliser — it carries no phosphorus or potassium.
Organic alternative
Gypsum + FYM
For the sulphur in organic systems, gypsum is the mineral source; combine with FYM for the nitrogen ammonium sulphate would have supplied.
Crops it is used on
Open a crop for its full nutrient schedule.
Common questions
Why do tea and potato growers prefer ammonium sulphate?
Because it supplies both nitrogen and a lot of sulphur, and its acidifying nature suits tea, which grows on and prefers acidic soils. Potato responds well to its ammonium nitrogen and to the sulphur, which supports tuber quality. It is a two-in-one fertiliser for these crops.
Does ammonium sulphate make soil acidic?
Yes — it is one of the more strongly acidifying nitrogen fertilisers. That is useful on alkaline and sodic soils, but on acidic soils it pushes the pH down further and should be balanced with agricultural lime over time.
Ammonium sulphate or urea for sulphur?
Urea has no sulphur at all. If the crop needs sulphur, ammonium sulphate delivers nitrogen and 24% sulphur together, which is often cheaper and simpler than buying a separate sulphur product — though on a bulk cereal with no sulphur problem, urea is the cheaper nitrogen source.
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.