Kinetics of Metal-Fulvate Reactions in Alkaline Soil

The changes in the distribution of competing metal ions during the reaction of Zn-FA, Fe-FA, Cu-FA and FA (fulvic acid) with alkaline soil for periods ranging between 1 and 30 days were determined by monitoring the concentrations of complexed zinc, iron, manganese, copper and calcium plus magnesium in supernatant soil solution. The reaction of Zn-FA, Cu-FA and Fe-FA were mainly influenced by Zn, Cu and the aqueous calcium plus magnesium concentration. There was an initial fast decrease in the concentration of soluble zinc, iron and copper followed by a slower rate of decrease. The initial fast reaction conformed to a first order reaction kinetics. The implication of metal cations interaction during the reaction of Zn-FA, Cu-FA, Fe-FA and FA with alkaline solution in the micronutrients nutrition of crops are indicated.