Effects of surface-applied lime and EDTA on subsoil acidity and aluminium

This paper reports a mechanism for chelation and removal of exchangeable Al from an acid subsoil. We treated soil columns with ethylenediamine tetraacetic acid (EDTA) and lime (CaCO3) to study the effects on subsoil ionic reactions. As water percolated through soils that had received surface applications of both EDTA and lime, significant levels of exchangeable aluminum were removed to a depth of 60 cm, whereas topsoil treatments of lime alone had little effect on subsoil exchangeable Al below 30 cm. Movement of Ca, Mg, and Fe are also presented as functions of EDTA and lime treatments. The data support the hypothesis that organic ligands can have a marked effect on the migration and subsequent ionic reactions of metal ions within the soil exchange matrix