POLY4 is the trademark name of Sirius Minerals Plc’s flagship fertilizer product. Made from polyhalite, a naturally occuring evaporite mineral, it contains four of the six macro-nutrients that are essential to plant growth.
Using POLY4 as the source of potassium, sulphur, magnesium, and calcium is more efficient and effective for farmers, delivering flexible and more sustainable fertilizer practices. It allows farmers to maximise the economic potential of their land, in terms of crop yield, quality and soil structure with one simple product.
Our high quality product is available in granulated, powdered or chipped form to meet the needs of our customers, taking into account their crop needs, blending requirements, application method and soil conditions.
Polyhalite is an evaporite mineral comprising of potassium, sulphur, magnesium and calcium, with the chemical formula K2SO4.MgSO4.2CaSO4.2H2O. While polyhalite deposits are known to occur elsewhere, none have the mineral quality or material extent of our defined North Yorkshire resource, which is the world's largest and highest grade.
The potential of polyhalite as a fertilizer was demonstrated in the 1930s, but the discovery of large alternative potassium sources and a shortage of high quality deposits meant polyhalite was not commercially developed. The recent discovery of large, high purity polyhalite deposits in North Yorkshire led to renewed interest in the mineral as a multi-nutrient fertilizer.