NPK 15 15 15 Sulfur Based Amino Acid Granular Compound Fertilizer. NPK is a fertilizer containing two or three elements of nitrogen, phosphorus and potassium. NPK 15 15 15 fertilizer is the most commonly used compound fertilizer formula, which is a balanced fertilizer; fertilizer npk 15 15 15 is a fertilizer formula,including spray and ammoniated granular fertilizers, and powdered water-soluble fertilizers, suitable for many crops. Huaqiang chemical group is a professional fertilizer manufacturer, mainly including NPK compound fertilizer, water-soluble fertilizer, BB fertilizer, potassium sulfate, urea, ammonium bicarbonate, etc., with an annual output of 4.5 million tons.