Roots Organics Elemental 9 lb 20% Calcium 4% MagnesiumRoots Organics Elemental macronutrient and micronutrient supplement was specifically created to augment calcium and magnesium levels and prevent deficiencies that can occur with fast growing plants. Elemental contains two absolutely essential macronutrients: Calcium, an essential nutrient for plant health due to its role in cell walls, membranes and other biochemical processes; and magnesium, which is a central component of the chlorophyll molecule.