A NEW ‘home-grown’ fertiliser is coming to the market thanks to a new mine underneath the North Sea.

The potash and sulphur product, PotashpluS, is being produced by ICL UK at its Boulby mine, in North Yorkshire, where its source, polyhalite, is being mined from beneath the sea.

In 2011, ICL UK (formerly Cleveland Potash) began mining polyhalite, a naturally occurring evaporite rock which occurs 100-150m below traditional potash seams. Boulby is ‘the first and only mine in the world’ extracting this mineral today, which will be sold and marketed under ICL’s trademark brand Polysulphate.

While it has been the UK’s sole potash producer for more than 40 years, in June, 2017, the company decided to cease potash production and focus its business on polyhalite. This restructuring involved ICL making a £3.2m investment at Boulby to convert existing plant for PotashpluS production using existing infrastructure and maintaining jobs.

The resulting product provides four essential plant nutrients in a single fertiliser – potassium, magnesium, calcium and sulphur, plus trace elements such as boron. It delivers 37% potash (part in the form of potassium sulphate and part as potassium chloride); 3% magnesium; 24% sulphur (as sulphate) and 8% calcium.

“This is an ideal combination of nutrients,” pointed out Scott Garnett, ICL UK’s agronomist. “Potassium aids photosynthesis and drives yields in many crops. Magnesium’s role in photosynthesis is well-known, in addition it is important for root development.

“Calcium is less well recognised, but it plays an important role in the growing tips of plants. Sulphur has become increasingly important as deposition from the atmosphere, due to industrial emissions, has reduced over the past 30 years or more.”

While the application of fertiliser sulphur is increasing across the UK, data from the British Survey of Fertiliser Practice suggested that more is needed, especially on grass.

Mr Garnett added: “The prolonged release rate of the sulphate in our product benefits the crop and is more aligned to its needs during growth. This makes it a highly efficient fertiliser and one that reduces the risk of losses through leaching. It is a product that will suit all soil types.”

It is available as a 3mm granular product that will spread accurately up to 36m, he also pointed out.