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*|
|Cereals||higher||50||20||100||14||11.7||6||3.6||17||12.2||Apply in early spring before the start of stem extension.|
|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.|
|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.