Use of catechol solutions as extractants for mobilisable iron in forest soils

Abstract

Abstract Recent work has focussed attention on the use of a plethora of inorganic extracts for characterizing iron in soil. Concern surrounds the disparity between the amounts of iron extracted by these reagents and (i) field identification of podzolic or spodic horizons and (ii) iron mobilization processes thought to be occurring naturally in soils. It is suggested here that a simple, organic extractant may be more suitable, particularly for characterizing natural iron mobilisation processes. A synthetic catechol extractant is compared to the iron extractabilities of (i) standard inorganic methods using sodium dithionlte and sodium pyrophosphate and (ii) aqueous leaf leachates. Catechol solutions and aqueous solutions from fresh oak leaves and pine needles extracted similar amounts of iron from A and B horizons of acid brown forest soils in Leigh Woods, South West England. Potassium pyrophosphate solution extracted on average twice as much iron as the organic solutions and sodium dithionite solution diss...