The properties, genesis and significance of a man‐made iron pan podzol near Castletownbere, Ireland

Abstract

Beneath a layer of artificially deposited peat debris, an eluvial E horizon and thin iron pan (Bsm) has developed in the upper part of the Ap horizon of a brown podzolic soil (Haplorthod) near Castletownbere, Ireland. The thickness of the E horizon and the depth of the pan are directly related to the thickness of the layer of peat debris.The original soil (Haplorthod) was strongly podzolized with a significant accumulation of organic carbon, iron and aluminium in the spodic Bs. The iron pan of the upper sequum, on the other hand, is rich in iron. This iron pan seems to have developed as a result of reduction of iron in the E horizon, transport of divalent Fp2+ cations and precipitation in the Bsm as Fe2(0H)3, after the peat layer was deposited. We conclude that podzolization and iron pan development were fundamentally different processes.The study suggests a fundamental change in the iron pan-blanket peat development sequence previously postulated by palaeoenvironmentalists in Ireland.

Characteristics and genesis of Inceptisols with placic horizons in the subalpine forest soils of Taiwan

“…Spodic horizons are base on the accumulation of organic C, Al, with or without Fe (Soil Survey Staff, 1999). Conry et al (1996) and Hseu et al (1999) also concluded that podzolization and placic horizon development were fundamentally different processes.…”

“…Several hypotheses have been proposed to explain the genesis of placic horizons (Crompton, 1952;Clayden et al, 1990;Conry et al, 1996;Hseu et al, 1999;Lapen and Wang, 1999). Clayden et al (1990) concluded that placic horizon formed from Fe, which was reduced and mobilized from the upper part of the pedon and then reoxidized and precipitated in the Bs horizon.…”

“…The genesis of placic horizon is still not completely understood. Several hypotheses have been proposed to explain this genesis (Crompton, 1952;Conry et al, 1996;Chen et al, 1989Chen et al, , 1995Clayden et al, 1990;Hseu et al, 1999;Lapen and Wang, 1999). Placic horizons are formed in a wide range of landscapes from temperate to tropical zone but are always associated with the climate condition under udic or perudic soil moisture regimes.…”

Geochemical characterization of placic horizons in subtropical montane forest soils, northeastern Taiwan

“…It retards vertical leaching of water, inhibits the growth of roots and may cause plant mortality (Lapen & Wang, 1999; Wu & Chen, 2005). The wetness of surface layers above a placic horizon can create difficulties in land use (Conry et al , 1996), especially for forestry management. Placic horizons occur in a wide range of latitudes, from temperate to tropical, but are always associated with udic or perudic soil moisture regimes (McKeague et al , 1983; Hseu et al , 1999; Pinheiro et al , 2004; Schawe et al , 2007; Jien et al , 2010).…”

Visual drainage assessment: A standardised visual soil assessment method for use in land drainage design in Ireland

“…Pan layers are noted, if present. Iron pans are the most easily identifiable as a black to dark reddish coloured horizon, 2-10 mm thick (Conry, 1996;Cunningham et al, 2001). A score of -1 is assigned if a pan is present or 0 if not.…”