Iron deficiency in crops is usually prevented and cured by the application of synthetic Fe chelates such as EDTA/Fe and the o,o-EDDHA/Fe. However their persistence in soil calls for the implementation of new alternatives that present less of a risk to the environment. This study therefore evaluated the biodegradable chelating agent [S,S]-EDDS as a new source for Fe fertilisation in calcareous soils in relation to its chemical reactivity. The suitability of [S,S]-EDDS/Fe as an Fe fertiliser in a calcareous soil was investigated and compared to the traditional synthetic chelates EDTA/Fe and o,o-EDDHA/Fe. Plant experiments with soybean (Glycine max), 57Fe isotopic labelling, and batch incubations were conducted in a calcareous soil. The Fe concentration of plants treated with [S,S]-EDDS/Fe was similar to those treated with EDTA/Fe. A similar Fe concentration to the o,o-EDDHA/Fe treatment was achieved using a double dose of [S,S]-EDDS/Fe. Despite the degradation of [S,S]-EDDS limiting the durability of [S,S]-EDDS/Fe in soil, the Fe bound to the degradation products may be a determining factor in improving Fe uptake and translocation to leaves in plants treated with [S,S]-EDDS/Fe compared to other Fe sources. Speciation studies by modelling and batch experiments also supported the lower reactivity of [S,S]-EDDS/Fe with calcium compared to that of EDTA/Fe, possibly contributing to the permanence of [S,S]-EDDS/Fe in the calcareous soil. This study demonstrated for the first time, that [S,S]-EDDS may be an environmentally sustainable alternative to traditional synthetic chelating agents such as EDTA or o,o-EDDHA for curing Fe chlorosis in susceptible plants in calcareous soil.