Abstract:
This study has been carried out to investigate the speciation of iron in the various, plant available and non-available, soil fractions and the efficiency of the Mango (Mangifera indica) plant leaf extract in mobilizing iron from the strongly-bound soil fractions of cultivated, forest and water logged soil samples which were collected around Jimma town. The soil samples were treated with the mango plant leaf extract and the level of iron the various fractions of the treated soil samples and untreated triplicates of each soil type (controls) was determined spectrophotometrically. Results of the soil property studies revealed that, all the three soil types were moderately acidic. The percent organic matter analysis indicated that, the forest soil has the highest organic matter content (19%), followed by the cultivated soils (15%) and the water logged soil had the least content (7%). The speciation study indicated that, the Mangifera indica plant leaf powder extract is able to mobilize a substantial amount of iron from the strongly bound fractions of all the three soil types. The concentration of iron in the water soluble and exchangeable fractions of all the soil samples were found to increase while in the recalcitrant fractions it was found to decrease. In the water logged soil, the leaf powder extract was able to bring up to 7% more concentration of iron from the strongly bound fractions to the water soluble fraction of the water logged soil than the concentration extracted in the untreated soil (control). Similarly, the iron concentration in the water soluble fraction of the forest soil increased by 5% and in that of the cultivated soil by 4%. On the contrary, the concentration of iron in the strongly bound fractions of all the soil samples was found to decrease although the decrease varied with the strength of binding in each fraction.
