Polysulphate™ calculator

Use the chart below to decide how much you need, and how much potassium, magnesium and calcium your polyhalite application will provide.

Crops Risk of deficiency Advised rate (kg/ha) Other nutrients applied (kg/ha) Notes*
    SO3 S Polysulphate K2O K MgO Mg CaO Ca  
Cereals higher 50 20 100 14 11.7 6 3.6 17 12.2 Apply in early spring before the start of stem extension.
  lower 25 10 50 7.5 6.2 3 1.8 8.5 6.1
Oilseed rape higher 75 30 150 21 17.4 9 5.4 25.5 18.4 Apply in early spring. Spring crops may be less susceptible to deficiency.
lower 50 20 100 14 11.6 6 3.6 17 12.2
Peas (for dried, vining and fresh markets) 25 10 50 7.5 6.2 3 1.8 8.5 6.1 Apply where soil is sandy, shallow or medium textured and contains little organic matter.
Brussels sprouts, cabbage, cauliflowers, calabrese 50 20 100 14 11.6 6 3.6 17 12.2 Apply where sulphur content of soils is low, e.g. light soils following wet winters where there is no history of organic manures application.
Grassland 40 16 80 11.2 9.3 4.8 2.9 13.6 9.8 Apply at the start of growth before each cut. May not be required before first cut on medium/heavy soils.

 

* Generally applications should be made where a deficiency has been recognised or is expected. This can be assessed through tissue analysis, crop observation or whether in a high-risk area. Refer to official recommendations for further details.