This European Standard specifies a method for the extraction of water-soluble calcium, magnesium, sodium and sulfur (in the form of sulfates), so that the same extract can be used for the determination of each nutrient required. The method is solely applicable to fertilizers listed in Regulation (EC) 2003/2003, Annex I [2]), for which a declaration of the water-soluble calcium, magnesium, sodium, and sulfur (in the form of sulfates) is provided for in this Regulation.