Comparison of the Fixation Kinetics of Chelated and Non-Chelated Copper in Semi-Arid Soils of Texas High Plains.

Chelated-micronutrient compounds are commonly used to reduce micronutrient fixation by soil constituents, thus enhancing their availability to plants. This study applied kinetic models to the examination of fixation mechanisms of chelated and non chelated copper (Cu) in three semi-arid soils of the Texas High Plains to enhance Cu management in these soils. Comparisons between the chelated and non-chelated Cu systems show that approximately, 22% more Cu was fixed in the non-chelated system within the first 14 days and 7% more by day 90. The fixation of available Cu in the non-chelated system was better described by the power function models, suggesting that reduction in available Cu in these semi-arid soils follow a somewhat non-liner trend over the experimental period of 90 days. However, within the chelated system, Cu fixation was better described by the second order model, suggesting a reaction rate that depends on the concentration of another reactant outside Cu. Findings highlighted the effectiveness of chelating agents in micronutrient management in these soils and the significance of timing even when micronutrients are applied in chelated forms. Findings from this study have more practical implications because the experiment was designed to ensure the application of findings to field settings.