POLYHALITE: A CHLORIDE-FREE MULTI-NUTRIENT FERTILIZER FOR ENHANCING SOIL FERTILITY AND SUSTAINABLE CROP PRODUCTION

Abstract

The secondary macronutrients calcium(Ca), magnesium (Mg) and sulphur (S) are being increasingly depleted from agricultural soils due to the excessive use of nitrogen, phosphorus and potassium (NPK) fertilizers. This led to multiple nutrient deficiencies limiting both crop yield and soil fertility. Polyhalite (K₂Ca₂Mg(SO₄)₄·2H₂O) is a naturally occurring marine evaporite mineral found 1,200 m below the England’s North Sea Coast and has become a promising multi-nutrient fertilizer alternative to conventional potassic fertilizers such as muriate of potash (MOP) and sulphate of potash (SOP) and delivering potassium (14% K₂O), calcium (17% CaO), magnesium (6% MgO) and sulphur (48% SO₃) in one chloride free application. Along with the impact on soil health and environmental sustainability, this review includes mineralogical origin, dissolution dynamics and agronomic performance of polyhalite in cereals, legumes, oilseeds, horticultural and tuber crops. Its slow-release dissolution enhances nutrient use efficiency and reduces leaching losses. It has a carbon footprint of just 0.034kg CO2e kg-1, far below MOP and sulphate of potash, and is globally certified organic; a multi nutrient fertiliser scientifically validated for environmentally responsible, sustainable crop production. field evidence shows yield increases of 20-30% for cereals, 7.5-29% for legumes and 6-14% horticultural crops.