MicroSource HEDTA Chelated Iron 4.5%, 2.5 GallonsHEDTA Iron 4. 5 is a HEDTA chelated iron solution designed for use in most soil applied liquid fertilizers and foliar sprays. Iron serves as a component of many vital enzymes such as cytochromes of the electron transport chain, and it is thus required for a wide range of biological functions. In plants, iron is involved in the synthesis of chlorophyll, and it is essential for the maintenance of chloroplast structure and function. Features and benefits