In a split-split plot design with three replicates, a vitro kinetic experiment was carried out during two months to study the effect of both individual applications of either of two sources of humic acids (HAs) react with (or without) Fe or Mn on desorption of both micronutrients from three calcareous soils varying in their active CaCO₃ contents. Each HA was applied at a rate of 100 mg kg^-1 soil. Each of Fe and Mn was added in the acetate form (CH₃COO) at a rate of 50 mg kg^-1 soil. Results showed that the application of HAs with Fe or Mn led to minimizing fixation of both ions on soil particles compared to the control soil (untreated soil). A kinetic study implied used three different models well described the rate of Fe and Mn desorption from the treated soils by having a high and significant coefficient of determination R² and low standard error SE. According to the rate constants of the used models, applications of either the two HA with Fe or Mn were associated with a significant increase in the rate of both ions desorption with some prefer ability to HAP (derived from pudrite) compared to HAC (derived from clover straw compost). Different mechanisms take place between CaCO₃ soil particles, HAs and Fe or Mn systems were discussed.