What is polyhalite?

Polyhalite chemical composition: K2SO4·MgSO4·2CaSO4·2H2O

Made up of four key nutrients that are key to healthy plant growth:

K2O ( Potassium) 14%
MgO (Magnesium) 6%
CaO (Calcium) 17%
S (Sulphur) 19%

How Polyhalite is formed (Geology & Origin)

Polyhalite is a naturally occurring mineral that formed roughly 260 million years ago, during the Permian period, when the region that is now northern England lay on the edge of the ancient Zechstein Sea. Hot, arid conditions caused this shallow sea to evaporate more quickly than it could be replenished, leaving behind thick layers of evaporite minerals - including polyhalite, along with halite and potash - that today form the basis of modern fertiliser production.

At Anglo American, we transform this naturally occurring polyhalite into POLY4, our low‑carbon, multi‑nutrient fertiliser designed for both conventional and organic farming. POLY4 is created through a simple process of crushing and granulating the polyhalite ore, preserving its natural nutrient profile of potassium, sulphur, magnesium and calcium.

While other producers market polyhalite under different product names, POLY4 reflects Anglo American’s commitment to delivering a scalable, sustainable, and nature‑based fertiliser that supports soil health, improves nutrient use efficiency, and provides season‑long nutrient release.

By delivering a more balanced and sustainable approach to fertilisation, POLY4 empowers farmers to achieve results while reducing the risk of waste and loss across the farm.

With POLY4, we're not just fertilising crops - we're cultivating a more sustainable future for global agriculture.

Helps improve yield and quality

POLY4 trials have shown a variety of quality improvements and overall, a median yield uplift of 3-5% globally, when compared to standard NPK and NPKS fertilisation programmes.

Optimising nutrient use

POLY4 releases available nutrients gradually, for longer availability over the growing period. The sustained release profile offers growers more flexibility of application timing.

POLY4 trials have typically shown greater nutrient uptake, allowing growers to optimise nitrogen rates and better manage their inputs.

Nutrient use efficiency (NUE) refers to the effectiveness at which plants use applied nutrients for growth and development.

POLY4’s neutral pH and combined team of nutrients including K, Mg, Ca and S, create ideal conditions for supporting improvements in NUE.

POLY4 provides nutritional tools to effectively optimise nitrogen (N) from both chemical and organic sources.

Better N efficiency can be achieved during conversion of total available N, provided from soil and fertilisers, into proteins. The nutrients supplied by POLY4, help drive nitrate conversion and protein metabolism

Supporting healthy soils

POLY4 is low in chloride, with a low salt index and a neutral pH, with no harmful effects on the delicate soil ecosystem. The calcium in POLY4 helps improve soil structure.