EXTRACTION OF DIFFERENT FORMS OF IRON PRE SENT IN A PETROCALCIC HAPLUSTOLL - COMPARATIVE-STUDY OF THE DITHIONITE-CITRATE-BICARBONATE (DCB) METHOD AND THE DITHIONITE-EDTA METHOD

Four methods have been used to extract iron (Fe) from different fracti ons in a Petrocalcic Haplustoll, The four extractants were pyrophophat e reagent (p), acid-oxalate reagent to), dithionite-citrate-bicarbonat e reagent (d) and dithionite-EDTA. Each reagent was thought to extract different forms of Fe, The relative efficiency of the iron extractant s was as follows: Dithionite-EDTA > DCB > Oxalato > Pyrophosphate, The most important amount of iron was found in the clay fraction, Dithion ite-EDTA pH:5.5 method dissolved Fe better than DCB method. The advant ages of this modified DCB method were: a) only a single extraction was needed; b) the working temperature was lower than the DCB traditional method.