Consumer advocacy teardown
Sulphate of Ammonia alternative & active ingredient dupe
Stop paying £7.50 for Westland. The bulk active is Agricultural ammonium sulphate 21% N — 64% less per working litre than a typical pack.
- Active
- Ammonium sulphate
- CAS
- 7783-20-2
- Dupe
- Agricultural ammonium sulphate 21% N
- Saving
- 64% / L
Saving is per litre of working-strength mix versus a typical pack price, not versus the DIY kit total. Shop prices move — always check the listing.
The Marketing Claim & The Catch
A typical 1.5 kg box pack of Westland Sulphate of Ammonia is about £7.50 in lawn & garden. That is a snapshot, not a live Amazon price — listings, sizes and deals move. The marketing line is that you are buying a finished lifestyle product, not a weighed chemical.
On the pack: Quick greening nitrogen for lawns, brassicas and leafy crops; and Acidifying feed for lime-hating plants.
The catch: 21% nitrogen as ammonium sulphate. The cardboard box is a portioned sack of a fertiliser merchants sell in 25 kg lots. It greens grass. It also acidifies — do not pile it on chalk-hating stone paths.
- “Quick greening nitrogen for lawns, brassicas and leafy crops”
- “Acidifying feed for lime-hating plants”
Proprietary Blend & Dosage Breakdown
The labelled active is Ammonium sulphate at 21%. Everything else in the pack is none (prills).
At 21% active, most of what you pay for is carrier and packaging. The brand is selling convenience, fragrance and a label — not a uniquely potent molecule.
Branded working strength is whatever comes out of the bottle. The bulk alternative is 21% Agricultural ammonium sulphate 21% N, mixed to 35 g/m².
- Labelled active
- Ammonium sulphate
- 21%
- Carrier
- None (prills)
- Retail pack
- 1.5 kg box · £7.50
The Active Chemical Alternative (Dupe Stack)
The dupe stack is Agricultural ammonium sulphate 21% N at 21% bulk. Indexed as CAS 7783-20-2, formula (NH4)2SO4. Buy it as 25 kg for about £18.00 from Amazon UK.
Working strength: 35 g/m². Indicative cost £0.03 per diluted litre — 64% below a typical branded pack on a per-litre basis, before you reuse leftover bulk.
Follow the mixing method and the supplier SDS. Wear the listed PPE. Do not mix incompatible oxidisers, acids or ammonia.
- Wear gloves. Avoid breathing dust. Broadcast 35 g/m² on a dry lawn, then water in. Keep off ponds.
- A 25 kg sack covers about 700 m² at 35 g/m². That is more than sixteen 1.5 kg boxes.
- Do not mix with lime in the same pass. Store dry.
Mixing desk
Dilution calculator
Switch between filling a sprayer and covering a measured surface. Figures are educational estimates from the listed ratio — always check the SDS.
Formula
Agricultural ammonium sulphate 21% N
- Concentrate
- 3,500 g
- grams of solid
- Water
- 5 L
- carrier volume
- Batch cost
- £2.52
- 5 L working solution
- Saved vs retail
- £14.98
- 86% · retail £17.50
Estimated coverage at the listed rate: 100 m².
Side-by-Side Price & Potency Comparison
Head-to-head comparison
| Measure | Retail brandedWestland | Raw active dupeDupeStack |
|---|---|---|
| Product | Sulphate of AmmoniaAmazon UK search — listing, not a confirmed seller | Agricultural ammonium sulphate 21% N |
| Pack / unit | 1.5 kg box · £7.50 | 25 kg · £18.00 |
| Active | Ammonium sulphate at 21%Carrier: None (prills) | 21% bulk(NH4)2SO4 |
| CAS number | Not disclosed on pack | 7783-20-2 |
| Working strength | Ready-to-use pack | Dilute 35 g/m² |
| Cost per litre | £7.50 / pack | £0.03 / L mixed from bulk |
| Headline saving | Baseline | 64% cheaper |
| COSHH / PPE | Follow the branded SDS | Gloves. Chemical-resistant gloves (nitrile or neoprene)Ventilation. Use outdoors or with mechanical extraction |
Active ingredient and cheaper alternative — FAQ
What is the active ingredient in Westland?
Westland Sulphate of Ammonia is labelled as Ammonium sulphate at 21%. The carrier is None (prills). Pack size: 1.5 kg box. The bulk equivalent we index is Agricultural ammonium sulphate 21% N (CAS 7783-20-2).
Is Agricultural ammonium sulphate 21% N safe on lawns?
Used at the listed working strength (35 g/m²), the dupe is the same chemistry as the branded pack for lawns, beds and pots. That is not a blanket all-clear: read the supplier SDS, wear the listed PPE, keep acids away from hypochlorite, and follow UK HSE/COSHH rules. Wellness teardowns are supplements, not medicines.
Is there a cheaper alternative to Westland Sulphate of Ammonia?
Yes. The bulk equivalent is Agricultural ammonium sulphate 21% N (CAS 7783-20-2). Indicative saving 64% per working litre versus a typical £7.50 pack. Working strength: 35 g/m². Live shop prices move.
How do you mix the Sulphate of Ammonia dupe stack?
Wear gloves. Avoid breathing dust. Broadcast 35 g/m² on a dry lawn, then water in. Keep off ponds. A 25 kg sack covers about 700 m² at 35 g/m². That is more than sixteen 1.5 kg boxes. Do not mix with lime in the same pass. Store dry.
DupeStack provides chemical concentration data and educational mixing guides. Always review official manufacturer Safety Data Sheets (SDS) and comply with UK Health and Safety Executive (HSE) and COSHH regulations when handling concentrated substances. Some links on this site are affiliate links.
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DIY stack · 64% / L vs branded
£32.00indicative kit · Amazon cannot add a mixed search kit as one basket