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Polyhalite is a naturally occurring evaporite mineral comprising hydrated sulphates of potassium, calcium and magnesium, with the chemical formula K2SO4.MgSO4.2CaSO4.2H2O.
Polyhalite will be mined by Sirius Minerals and used as a unique four-in-one macro-nutrient fertilizer to provide a rich source of potassium, sulphur, magnesium and calcium. It can also be combined with other fertilizers as a feedstock to create other commonly used fertilizer blends.
Independent tests have proven it is suitable for widespread commercial farming, including organic farming and is a low carbon footprint, high nutrient content fertilizer which has excellent nutrient availability to the plant. 
The Company's production of polyhalite will help to provide a solution to the challenge of global food security as York Potash will become one of the most significant large scale suppliers of multi-nutrient fertilizers.

Technical Specifications
POLY4 is the powder and granulated product that will be produced from the York Potash Project and is a granular presentation of micronized polyhalite suitable for common agricultural fertilizer spreaders. POLY4 has been proven to be a fully soluble multi-nutrient fertilizer suitable for soil application at all commercial application rates, is pH neutral and has no negative effect on soil conductivity at commercial application rates.
Polyhalite has also been granted authorisation for use in organic systems certified by the Soil Association and the Organic Farmers and Growers.  
160 countries worldwide have organic farming systems which represents a total of 37 million hectares globally (IFOAM, 2010). Strict regulations, known as ‘standards’, define what organic farmers can and cannot do – and place a strong emphasis on the protection of wildlife and the environment.  
Balanced fertilization
Nutrients are complimentary to each other and a deficiency in any of them will limit crop growth and quality, the so-called “law of the minimum.” Balanced fertilization, particularly of the six macro-nutrients (nitrogen, phosphorus, potassium, sulphur, magnesium and calcium), is essential to obtain optimal crop yields. With most regions experiencing the challenges of multiple nutrient deficiencies, balanced fertilization will have to be at the centre of achieving sustainable growth to feed the world.
Polyhalite is a unique natural and organic mineral that contains four macro-nutrients that are known to be important for crops and soils: potassium, sulphur, magnesium, and calcium. The nutrient breakdown of pure polyhalite – K2SO4.MgSO4.2CaSO4.2H2O – is as follows:potassium: 16% as K2O; sulphur: 21% as S; magnesium: 7% as MgO; and calcium: 19% as CaO. Each of these nutrients play a vital role in the crop life cycle.


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