Dihydrate Poly halite
A straight potassium fertiliser specified under the Fertiliser Control Order, 1985 (Schedule I, Part A, 1(c), item 6). Key notified values: Water soluble potassium 12.5 min; Water soluble Calcium 15.0 min; Water soluble Magnesium 5.0 min. Added by S.O. 2324(E) of 13 Jul 2020.
Tip This is a compliance tool, so it is best viewed on a desktop or laptop. The phone version shows everything too.
Specification
As notified in the Order, line by line. Values are per cent by weight unless the line says otherwise.
How to read this table
- Minimum means the product must contain at least this much; maximum means not more than this (moisture, impurities and heavy metals have a maximum).
- Per cent by weight means grams in every 100 g of product: 0.5 per cent zinc is 5 g of zinc in every kg.
- P₂O₅ and K₂O: phosphorus and potassium are declared as their oxides. To get the element, multiply P₂O₅ by 0.436 and K₂O by 0.830.
- Tolerance: a lab result may fall slightly short of the notified value before the sample is called non-standard; the limits are in Schedule I, Part B.
- S.O. … (E) is the number of the Gazette notification that made a change; “in force” (w.e.f., with effect from) is the date it started to apply.
| Parameter | Notified value | |
|---|---|---|
| (i) | Moisture per cent. by weight, maximum | 1.0 |
| (ii) | Water soluble potassium (as K₂O) per cent by weight, minimum | 12.5 |
| (iii) | Water soluble Calcium (as CaO) per cent by weight, minimum | 15.0 |
| (iv) | Water soluble Magnesium (as MgO) per cent by weight, minimum | 5.0 |
| (v) | Sulphate Sulphur (as S) per cent by weight, maximum | 17.5 |
| (vi) | Cadmium (as Cd) per cent by weight, maximum | 0.0025 |
| (vii) | Arsenic (as As) per cent by weight, maximum | 0.01 |
Tolerance: how far a sample may fall short of a declared value is set in Schedule I, Part B; see the tolerance limits.
Test methods (Schedule II, Part B): method 2: Moisture (oven dry method); method 5: Potassium (sodium tetraphenylboron method); method 24: Total sulphur.
Check a lab report
Compare the results of a lab test with this specification, line by line, including the tolerance allowed in Part B. Enter each result as on the report (per cent by weight unless the line says otherwise). A guide only: the report of a notified laboratory decides whether a sample is standard.
| Parameter | Notified | Lab result | Result |
|---|---|---|---|
| (i) Moisture | 1.0 maxtolerance 0.3 units | ||
| (ii) Water soluble potassium | 12.5 mintolerance 0.5 units | ||
| (iii) Water soluble Calcium | 15.0 mintolerance 0.5 units | ||
| (iv) Water soluble Magnesium | 5.0 mintolerance 0.5 units | ||
| (vi) Cadmium | 0.0025 max | ||
| (vii) Arsenic | 0.01 max |
Not checked here: Sulphate Sulphur.
Notification history
- 13 Jul 2020S.O. 2324(E): entry inserted (in force 14 Jul 2020)
- 22 Sep 2022S.O. 4477(E): line (ii) substituted (was “13.5”)
- 22 Sep 2022S.O. 4477(E): line (iii) substituted (was “16.5”)
- 22 Sep 2022S.O. 4477(E): line (iv) substituted (was “5.5”)
- 22 Sep 2022S.O. 4477(E): line (v) substituted (was “18.5”)
Before you make, label or buy it
- Manufacturers and importers: each declared value on the label must meet the limit above; samples are tested by the notified method.
- Dealers and farmers: check that the product name and declared contents on the pack match this specification, and keep the bill with the batch number.
- Doses are not part of this specification: follow the label and local agricultural advice.
Questions? Ask our agri expert on WhatsApp.
Show more straight potassium fertilisers 6 others
Consolidated by NanoKheti from the Fertiliser (Inorganic, Organic or Mixed) (Control) Order, 1985, as amended up to the Ninth Amendment Order, 2026 (S.O. 4045(E), 22 Jul 2026), for reference. The Gazette text is authoritative; this page is not legal advice. Check the notification before labelling, licensing or buying. Checked for later changes on 20 October 2026.