Timing for a sustainable fertilisation of Glycine max by using HBED/Fe 3+ and EDDHA/Fe 3+ chelates.

BACKGROUND: Efficient use of Fe chelates is crucial to avoid environmental risks and reduce economic losses. HBED/Fe3+ has been recently approved by the European Union for soil fertilisation, but studies delving into the best timing for its application are necessary. In this work, a batch incubation experiment and two biological experiments were developed to determine the optimal physiological stage for a sustainable application of HBED/Fe3+ in soil fertilisation compared with EDDHA/Fe3+ fertilisers using57 Fe.

RESULTS: HBED/Fe3+ demonstrated a high durability in soils and soil materials, maintaining more than 80% of Fe chelated after 70 days, and its application at an early physiological stage resulted in a high Fe accumulation in soybean and soil after 36 days. In contrast, the stability of EDDHA/Fe3+ decreased because of the retention of its lowest stable isomers. The best timing for chelates application was confirmed in a 52 day experiment. The application of HBED/Fe3+ at the early stage increased the Fe translocation to fruits; while o,o-EDDHA/Fe3+ accumulated more Fe in fruits when added at the fructification stage.

CONCLUSION: The high HBED/Fe3+ stability in calcareous soil requires a differentiate application timing, and its addition at early physiological stages leads into the most efficient fertilisation. © 2016 Society of Chemical Industry.