Ortho Silicic Acid (OSA) 2.0% WSL
A beneficial element fertiliser specified under the Fertiliser Control Order, 1985 (Schedule I, Part A, 1(j), item 1). Key notified values: Ortho Silicic Acid [Si(OH)₄] 2.0 / 0.6. Added by S.O. 5887(E) of 1 Dec 2018.
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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.
- 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 | |
|---|---|---|
| 1. | Ortho Silicic Acid [Si(OH)₄], per cent. by weight, minimum / Plant available Silicon (Si) equivalent, per cent by weight, minimum | 2.0 / 0.6 |
| 3. | Matter insoluble in water percent by weight, maximum | 0.5 |
| 4. | Specific Gravity (g/m) | 1.07-1.15 |
| 5. | Sodium (as Na) per cent. by weight, Maximum | 0.10 |
| 6. | Total Chloride (as Cl) per cent. by weight, Maximum | 4.00 |
Tolerance: how far a sample may fall short of a declared value is set in Schedule I, Part B; see the tolerance limits.
Test method (Schedule II, Part B): method 29: Plant-available silicon, Si(OH)₄ (CaCl₂ extraction, UV).
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 |
|---|---|---|---|
| 1. Ortho Silicic Acid [Si(OH)₄] | 2.0 mintolerance 0.2 units | ||
| 1. Plant available Silicon (Si) equivalent | 0.6 mintolerance 0.06 units | ||
| 3. Matter insoluble in water | 0.5 max | ||
| 4. Specific Gravity (g/m) | 1.07-1.15 | ||
| 5. Sodium | 0.10 max | ||
| 6. Total Chloride | 4.00 max |
Notification history
- 1 Dec 2018S.O. 5887(E): entry inserted
- 31 May 2021S.O. 2126(E): line 6 substituted (was “0.5”)
- 22 Sep 2022S.O. 4477(E): a line omitted (it read: “2. pH (1% solution in distilled water @ 20°C) 1.7-2.2”)
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.
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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.