Fertilization effect of Cu-EDTA chelate on soil pH and redox conditions in a flooded neutral soil

Abstract

Copper chelates are applied to correct copper micronutrient deficiencies in soils and one of the most commonly used is the synthetic chelate Cu-EDTA (Cuethylenediaminetetraacetate). The effectiveness of chelates is due to their capacity to maintain Cu in the soil solution. This is related to their stability which can be modified by the physico-chemical characteristics of the soil and especially by its pH and redox potential. Under water saturation conditions, a decrease in, or loss of, molecular oxygen leads to redox reactions that influence both the pH of the soil and the chemical forms of the ions and molecules present in the soil solution. An increase in the oxidation potential (Eh) (reducers conditions) influences the mobilization of metals adsorbed onto certain soil fractions because it enhances the concentration of reduced forms and thus the availability of metals in the soil. The aim of this study was to evaluate the effect of the Cu-EDTA chelate on pH and pe (pe=Eh(mv)/59.2) in a flooded neutral soil and to relate this effect to variations in the amount of Cu in the soil solution.