Agricultural Grade Zinc Oxide is used as a trace element additive for soils in the garden(premix). It is specially processed zinc oxide without heavy metals. It is dark brown to black in color. Produced as 72% and 75% ZnO according to customer demand in the United States for Zinc Supplementation. For Zinc Deficiency in soils please supplement 2-3 lbs per 250 square feet. As a side dress please use 1/8 cup per established plant and water down to the root zone.