Kinetics of Iron Fulvates Reaction in a Calcareous Soil

The kinetics of reactions of Fe-FA₁ (Comp.), Fe-FA₂ (PM); Fe-FA₃ (SS); Fe-FA₄ (PR) and Fe-FA₅ (BGs) with calcareous soil conformed to first order reaction. The rate constants (K) of displacement of Fe from Fe-FA₁; Fe-FA₂, Fe-FA₃; Fe-FA₄ and Fe-Fa₅ were 0.0049, 0.0062, 0.0019, 0.0028, 0.0016 h⁻¹, respectively in a calcareous soil. A plot of concentration of Fe-fulvate, Cu-fulvate, Zn-fulvate vs l-e^ks gave a linear relationship, indicating that Fefulvates reactions in a calcareous soil obey the pseudo-parallel first order kinetics. Agreement between the value of overall rate constant of Fe displacement from iron fulvate and summation of formation of Ca-fulvate (K₂), Zn-fulvate (K₃) and Cu-fulvate (K₄) as predicted by the proposed kinetic model was excellent. The calculated diffusion coefficient of iron during its movement into the soil matrixfalls in/he order: Fe-FA₂ > Fe-FA₄ > Fe-FA₁ > Fe-FA₃ > Fe-FA₅.