Most soils contain sufficient amounts of Fe for plant use; however, most of these amounts are found mainly in unavailable forms for plant use. Applying Fe to soil is associated with rapid sorption by soil; also, application of micronutrient elements might affect Fe availability in soil. This paper discuses the effects of applying Fe, Zn or Mn fertilizers on AB-DTPA-Fe extractability; also it investigates the fitness of Fe sorption data to different kinetic models to explore the possible mechanism or mechanisms that might affect Fe sorption in soil. The results reveal that application of either Fe, Mn or Zn had no significant effect on AB-DTPA- Fe in the Typic Torriorthent and Typic Haplocalcid soils. Mixed application of Fe + Mn, Fe + Zn, Zn + Mn or Fe+Zn+Mn increased AB- DTPA- Fe extractability significantly in both soils. The increase in the amount of AB-DTPA-Fe was about 4 folds in the Typic Torriorthent soil, and 40 folds in the Typic Haplocalcid one. Fitting the sorption data of Fe of nine periods of contact between soil and added metals to the different kinetic models showed that the simple Elovich and parabolic diffusion models seemed to be the most fitting models for describing Fe sorption kinetics in the Typic Torriorthent soil, while the first order model was the most fitting model to describe Fe sorption kinetics in the Typic Haplocalcid soil. |
