Commercial iron ethylene diamine di(hydroxyl phenyl acetic acid) (FeEDDHA) fertilizers containing the same Fe percent and applied at the same FeEDDHA rate control Fe deficiency chlorosis (IDC) differently due to differing ortho, ortho FeEDDHA (o,o-FeEDDHA) concentrations. This study: 1) determined the effect of o,o-FeEDDHA concentration on controlling IDC in soybeans (Glycine max L. Merr.); and 2) developed a soil-stability test using a simple colorimetric analysis method to determine the relative quality of soil-applied FeEDDHA fertilizers. A greenhouse experiment was conducted where nine FeEDDHA fertilizers were applied at two FeEDDHA rates. The soil-stability test compared these fertilizers with two incubation methods which utilized three soils and four incubation times, and extracts were analyzed by two methods. The results of these experiments suggest that soil-applied FeEDDHA fertilizer quality is contingent upon its o,o-FeEDDHA concentration, and the fertilizer quality can be determined by a soil-stability test with a colorimetric analysis method.