China Kieserite Fertilizer Factory: Effective Content Determines the Kieserite Fertilizer Price
Recently, Rongqing Chemical received a 2025 Kieserite Fertilizer Price inquiry from a client in Indonesia.The customer asked whether we can supply and quote for the following specification:
Magnesium (MgO): 28–36%,
Sulfur (SO₃): 11%.
Our answer is absolutly Yes.
Before giving a detailed reply, let’s share some insights into China’s kieserite fertilizer industry.
1. Understanding Kieserite and Its Source
As is well known, Kieserite is a widely used dual-nutrient fertilizer containing both Magnesium and Sulfur.It is industrially synthesized by reacting magnesium oxide (MgO) with sulfuric acid (H₂SO₄).
Magnesium oxide is derived from natural magnesite (MgCO₃). Rongqing Chemical’s kieserite fertilizer plant is located in Yingkou, Liaoning, known as “China’s Magnesium Capital”, where we have stable access to high-grade magnesite resources.
After calcination, High-Quality magnesite yields 92–95% MgO, with other available MgO purity such as 90%, 88%, 80%, 65%, and 52%.When MgO of different grades reacts with sulfuric acid,
the resulting kieserite fertilizer price will naturally have varying MgO purity.
(For more information about Rongqing Chemical’s kieserite fertilizer factory in China, please watch our Youtube Video: Kieserite Factory Rongqing Chemical).
In both Chinese and international magnesium fertilizer standards, the MgO content is the key quality anchor for product classification.
Therefore, when Indonesia clients purchase kieserite fertilizer, they always specify the MgO content — since different MgO levels directly affect the kieserite fertilizer price.
2. Common Kieserite Fertilizer from Rongqing Chemical
Rongqing Chemical regularly produces and exports the following good sale major types of Kieserite Fertilizers:
1.Kieserite: W-MgO 5% min, Total MgO 20% min
2.Kieserite: W-MgO 20% min, Total MgO 25% min
3.Kieserite: W-MgO 24–25% min, Total MgO 25% min
4.Kieserite with Boron and Zinc:Total MgO 25% min, W-MgO 24–25%, B 1% min, Zn 2% min
✅Product Name: Kieserite Granular (Magnesium Sulphate Monohydrate)
✅Granule Size: 2–5 mm
✅Color Options: Blue, Pink, White or OEM/ODM
3. Quality Indicators Beyond MgO
In addition to MgO content, kieserite quality is also defined by parameters such as:
🔹Total MgO and Water-soluble MgO
🔹Sulfur trioxide (SO₃) or Sulfur (S) content
🔹Chloride ions (Cl⁻)
🔹Heavy metal impurities
🔹… …
Each international market segment — whether in Asia, Europe, or South America — has different technical standards and preferences. These variations are important factors when matching suppliers and buyers for long-term cooperation.
(For details on Rongqing Chemical’s COA of Kieserite Fertilizer, please see our Kieserite Fertilizer COA page.)
4. Chemical Conversion: Understanding the Inquiry Specification
Let’s return to the Indonesian customer’s specification:
MgO: 28–36%, SO₃: 11%.
This MgO figure refers to total magnesium oxide content.The SO₃ percentage is not a common domestic indicator in China, but we can easily convert it using basic chemical ratios.
🔹Atomic weight of S = 32
🔹Molecular weight of SO₃ = 80
🔹Therefore, S/SO₃ = 32 ÷ 80 = 0.4
If SO₃ = 11%, then S = 11% × 0.4 = 4.4%
The ratio of S to MgO: S/MgO = 32 ÷ 40 = 0.8 is approximately 0.8.
Thus, the water-soluble MgO (W-MgO) content can be calculated as 4.4% ÷ 0.8 = 5.5%.
✅ Final Composition Equivalent:
🔹Total MgO: 28–36%
🔹Water-Soluble MgO (W-MgO): 5.5%
5. Supply Capacity and Price Advantage
For this grade of kieserite fertilizer required by the Indonesian customer,Rongqing Chemical has a daily production capacity of 500 tons, supported by an independent R&D team capable of formula customization and product optimization.
With direct supply from China’s kieserite source factory, we ensure our partners enjoy the most competitive kieserite fertilizer price and reliable quality assurance.
We welcome all inquiries from global buyers seeking trusted Chinese suppliers of kieserite and magnesium sulfate fertilizers.
📩 Contact Rongqing Chemical today for your 2025 kieserite fertilizer price quotation.
• Contact Rongqing Chemical:
📩 : marketing@rqsulfates.com; info@rqsulfates.com (Ms. Tang)
📞:86-151-1140-0823 | Official
Web: https://www.rqkieserite.com
Rongqing Chemical
Rongqing Chemical Co. Ltd, established in 1991, is a China-based kieserite Manufacturer & Exporter. Located in Yingkou Liaoning -the China magnesium We focus on kieserite,magnesium sulfate
