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Multi-nutrient mineral fertiliser offers slow S release option rBoulby said to be first polyhalite mine in world

Polyhalite fertiliser PotashpluS is a 50:50 mix of Polysulphate and MOP.

By Marianne Curtis DEVELOPING a new range of granular speciality fertilisers based around Polysulphate (polyhalite) is the goal of ICL UK, which has recently brought PotashpluS to the market. The company is based at Boulby Mine near Saltburn, Cleveland, and ceased mining muriate of potash (MOP) in June, switching its operations to mining and processing polyhalite and producing PotashpluS using its existing compaction plant, which has undergone a £3.2 million upgrade to ensure product quality. Boulby is said to be the first polyhalite mine in the world. Mining began in 2011 for a 20,000-tonne bulk sample. Since then one million tonnes have been mined and the process is now fully industrialised, explains ICL UK sales and marketing director Howard Clark. “Polyhalite is a naturally-occurring evaporite mineral that provides four essential plant macronutrients in a single fertiliser; potassium, magnesium, calcium and sulphur. It also contains trace elements such as boron.” ICL has branded the mineral Polysulphate.

Manufacture To manufacture PotashpluS, powdered Polysulphate and MOP are put through a compactor. The powder is fed in under pressure to make a flake which is then crushed to make small chips of material. Currently, more than 90 per cent of Polysulphate is exported, says Mr Clark. The mine is about 25 miles from Tees Dock, located on the River Tees, which has rail reception, road reception and road and sea dispatch. Boulby Mine is linked to the port by rail. PotashpluS is a 50:50 mix of Polysulphate and MOP. It contains 30.7 per cent of potassium as potassium sulphate and potassium

Key points n Polyhalite, brand name Polysulphate is a mineral containing K, Mg, S and Ca n Sulphur release is steady and in line with crop needs n Manufacture and marketing of PotashpluS, based on Polysulphate with added MOP is fully underway at ICL UK’s Boulby Mine in Cleveland n Early trials have shown an 8 per cent yield advantage in potatoes when using PotashpluS compared with MOP n ICL plans to extend its speciality fertiliser range

chloride; 1.8 per cent of magnesium as magnesium sulphate; 9 per cent of sulphur as sulphate; and 5.7 per cent of calcium as calcium sulphate. Richard Ward, ICL UK Polysulphate business manager, says it is positioned as a straight fertiliser but can be used in a blend. “Particularly in spring it offers a way to apply sulphur with potassium decoupled from nitrogen. For peas and beans which do not require N it offers a different option.

“It is suitable for all soil types and with acidic soils where ammonium sulphate should not be used this product can help.” The product allows even distribution of nutrients and can be placed, says ICL UK agronomist Scott Garnett. “It spreads accurately to 36 metres meaning fewer passes on the field. It is an ideally balanced fertiliser of potassium and sulphate with additional benefits of other macronutrients.”

Sulphur release Mr Clark says sulphur release from Polysulphate products is steady and in line with crop needs. “You don’t need to put as much S on as for ammonium sulphate.” The company has conducted trials on potatoes using the same amount of potash on areas treated with either MOP or PotashpluS. PotashpluS resulted in an 8 per

RECOMMENDED DOSE OF ICL POTASHPLUS High K demanding crops Crops Sugar beet, potato Recommended dose of ICL PotashpluS (kg/ha) 600-900

p27 Oct12 KH BB TR.indd 2

Moderately K demanding crops Oilseed rape, maize, fodder, peas 200-300

Cereal crops Wheat, small grains 200

It [polyhalite] is suitable for all soil types and with acidic soils where ammonium sulphate should not be used this product can help RICHARD WARD cent increase in yield over MOP, says Mr Garnett. ICL plants in the Netherlands and Germany are producing PKpluS compounds where Polysulphate partially replaces MOP and a proportion of the potassium content is in sulphate form, allowing flexible use in many crops, according to Mr Ward, who adds that NPKpluS compounds could also be a future option. OCTOBER 12 2018 | 27

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Farmers Guardian 12th October 2018  

Farmers Guardian 12th October 2018