عنوان مقاله [English]
Organic acids exuded by plant roots increase solubility of soil micronutrient complexes. This study was carried out to evaluate adsorption isotherms of 4 acidic and 4 calcareous soils at presence of organic acids (citric, malic and oxalic acids). Iron sorption and desorption isotherms are defined in to two systems including; system 1; soil-water-metal, system 2; soil-water-organic acid-metal). Data fitted to different adsorption/desorption isotherms model including Langmuir (Cs= kbCe/ 1+kCe) and Frundlich (Cs=kCe1/n) and appropriate model developed for quantitative behavior of iron adsorption/desorption. The results showed that in acidic soils, Fe adsorption data fitted well with Frundlich (R2>0.98, P0.94, Poxalic acid>malic acid>control, respectively. It can be concluded that complexing organic acids with Fe decrease its adsorption and promote availability for plant.