Polyhalite is a new natural fertilizer produced and sold only by ICL Fertilizers as Polysulphate, and field trials have proven that it is an effective crop fertilizer. It is found over 1,200m below the Earth’s surface, under the North Sea along England’s North East coast. We mine the substance from the polyhalite layer of rock, deposited 260 million years ago.

Polyhalite is a multi-nutrient fertilizer. It contains readily available sulphur plus potassium, magnesium and calcium which ensures increased crop yields and improved crop quality. In September 2010, we reached the main polyhalite seam with samples being brought to the surface for the first time – ever. And with surveys showing that potash reserves are dropping globally, there’s never been a better time to mine this exciting new fertilizer.

  • 48% SO3 as sulphate
  • 14% K2O as from sulphate of potash
  • 6% MgO as from magnesium sulphate
  • 17% CaO as from calcium sulphate



Polyhalite was deposited around 260 million years ago. At that time, the Permian era, Europe was much further south. Boulby was situated on the edge of a broad, shallow ocean called the Zechstein Sea. The prevailing hot and dry conditions at the time meant it evaporated quicker than it could be re-filled, leaving behind polyhalite, halite and potash minerals that we mine today.

Polysulphate is the product derived from the polyhalite mineral that lies 150m to 170m beneath the Potash Horizon at Boulby Mine. It is available in its natural state and is approved for organic use by Soil Association and Organic Farmers & Growers.




In a world where populations continue to grow and the food demand consistently increases, it’s important to farm as efficiently and sustainably as possible. This is where polyhalite, our new natural jewel, provides the answer. Polyhalite is available in its natural state. There are no chemical processes meaning it is a fully organic, sustainable fertilizer with a low environmental footprint.

Both a granular and powder product, this fertilizer has fantastic spreading characteristics and can be used alongside other fertilizers such as nitrogen, complementing their benefits. UK field trials have shown a 40% yield improvement with the application of Polysulphate. What’s more, Polysulphate helps to replace the potassium lost during harvest times, particularly with straw-like crops such as cereals, making it a complementary addition to routine fertilizer cycles.

Visit the Polysulphate website to learn more.