Polysulphate-based fertiliser recommended

ICL UK is recommending the use of its Polysulphate-based fertiliser products this autumn to boost crop health, optimise uptake of mineralised nitrogen and minimise loss of valuable nutrients through drainage or run-off. 

Polysulphate is the brand name for Polyhalite, a naturally occurring mineral rich in plant nutrients – potassium, sulphur, calcium and magnesium – extracted by ICL UK at its Boulby mine in East Cleveland. 

ICL’s Agronomist Scott Garnett said: “Almost 90% of UK soils, both arable and grassland, are now deficient in sulphur, according to independent soil analysis results. But sulphur is crucial to uptake of available nutrients, particularly mineralised nitrogen, in the autumn.” 

Similarly, applications of phosphate and potash in England and Wales has declined over the past 25 years with many soils now falling below the desired soil index level of 2. Regular, full analysis of soils is an important management tool to manage the risk of inadequate soil nutrients and maintain healthy soils. 

Based on commercial experience and trials since Polysulphate was launched in 2016, ICL UK recommends autumn applications to ensure efficient uptake of available nutrients. Trials on winter wheat have shown a 40% increase in phosphate uptake and 28% more nitrogen taken up. In part this efficient use of available nutrients is aided by the prolonged release of sulphur from Polysulphate-based products over some 50 days, compared to release over five to ten days with products such as ammonium sulphate and sulphate of potash.

“After autumn treatment, crops develop larger and more robust roots. So they grow away faster in the spring and are able to produce higher yields and improved quality,” said Mr Garnett. “We recommend autumn and spring applications for winter crops. On average, arable yield increases have been: 10% in cereals; 12% in potatoes; 13% in oilseed rape and 22% in peas. Improved quality parameters include longer shelf life for vegetables; higher oil percentage in oilseed rape and reduced sugars/ acrylamide in wheat and potatoes. 

“While in grassland, we have seen an average yield increase of 11% plus increased dry matter and crude protein levels.” 
ICL also believes Polysulphate products have a part to play in the farming industry’s drive to achieve net zero emissions and reduce the carbon footprint. 

“Polysulphate has the lowest carbon footprint of any fertiliser at just 0.03kg CO2e/kg,” says Howard Clark, UK Business Sales Lead for ICL UK. “And we are working to reduce that further. It has a neutral pH and does not contain any nitrogen. Therefore, there are no losses to the environment and much less risk of losses through leaching. 
“It is a natural mineral and accepted by organic farming organisations. Therefore, it is a product that farmers seeking to become sustainable should consider seriously.” 

Polysulphate is available to use as a straight, or in blend. It is also available in the ICL FertiliserpluS range of products.