Sodium calcium edetate, an EDTA by-product, is accustomed to bind metallic ions during the apply of chelation therapy, like for treating mercury and guide poisoning. With hard drinking water irrigation the soil is alkaline. It will take time to reduce the pH. This EDDHA iron saved the gardenias from chlorosis. https://myleszslev.thechapblog.com/33218960/an-unbiased-view-of-fertilizer-for-precision-agriculture