Kieserite vs Epsom Salt: Which Magnesium Sulphate Is Right for Your Fertilizer Program?
Magnesium is a central element in chlorophyll production, and magnesium deficiency directly reduces crop yield and quality. When sourcing magnesium sulphate fertilizers, buyers often face a choice between two common forms: kieserite (monohydrate magnesium sulphate, MgSO₄·H₂O) and Epsom salt (heptahydrate magnesium sulphate, MgSO₄·7H₂O).
Understanding the difference helps agri-importers and fertilizer formulators select the right product for their market.
1. Kieserite — Monohydrate Magnesium Sulphate
Kieserite contains approximately 16–17% MgO and only one molecule of water. It is a slow-release, granular fertilizer ideal for soil application.
Key advantages:
Slow release: magnesium is released gradually over the growing season, reducing leaching loss
Low caking: granular form stores well in bulk, even in humid tropical climates
High MgO content: more magnesium per tonne compared with heptahydrate
Suitable for: compound fertilizer raw material, direct soil application, fruit orchards, oil palm, sugarcane, and field crops
Jinlida's kieserite is produced at our Bohai Bay production base and is available in granular form with flexible bulk packaging for sea shipment.
2. Epsom Salt — Heptahydrate Magnesium Sulphate
Epsom salt contains approximately 9–10% MgO and seven molecules of water. It is highly water-soluble and fast-acting.
Key advantages:
Fast-acting: immediately available to plants through foliar or fertigation application
High solubility: dissolves quickly for spray and drip irrigation systems
Suitable for: foliar spray, hydroponics, greenhouse crops, and quick magnesium-deficiency correction
Quick Comparison
| Parameter | Kieserite (Monohydrate) | Epsom Salt (Heptahydrate) |
|---|---|---|
| MgO content | ~16–17% | ~9–10% |
| Solubility | Slow | Fast |
| Release rate | Slow / controlled | Immediate |
| Best use | Soil application, bulk blending | Foliar spray, fertigation |
| Storage stability | Excellent (low caking) | Prone to caking in humidity |
Which One Should You Import?
If your market focuses on soil-applied granular fertilizers, compound fertilizer production, or plantation crops — kieserite is the more cost-effective and stable choice.
If your market focuses on foliar fertilizers, water-soluble blends, or hydroponic nutrients — Epsom salt is the preferred form.
Many of our clients import both forms to serve different segments of their agricultural market.
About Jinlida Chemical
Qingdao Jinlida Chemical Co., Ltd. has been exporting kieserite and magnesium sulphate fertilizers since 2004. Our production bases in Weifang and Dalian leverage the rich salt-chemical resources of the Bohai Bay region, ensuring stable bulk supply and consistent quality for global agricultural clients.
For technical datasheets, SGS inspection reports, or sample requests, please email info@jinlidaqd.com or call +86-15589853260.
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